alloc_flags is a bitmask of flags but it is signed which does not
necessarily generate the best code depending on the compiler. Even
without an impact, it makes more sense that this be unsigned.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page allocator iterates through a zonelist for zones that match the
addressing limitations and nodemask of the caller but many allocations
will not be restricted. Despite this, there is always functional call
overhead which builds up.
This patch inlines the optimistic basic case and only calls the iterator
function for the complex case. A hindrance was the fact that
cpuset_current_mems_allowed is used in the fastpath as the allowed
nodemask even though all nodes are allowed on most systems. The patch
handles this by only considering cpuset_current_mems_allowed if a cpuset
exists. As well as being faster in the fast-path, this removes some
junk in the slowpath.
The performance difference on a page allocator microbenchmark is;
4.6.0-rc2 4.6.0-rc2
statinline-v1r20 optiter-v1r20
Min alloc-odr0-1 412.00 ( 0.00%) 382.00 ( 7.28%)
Min alloc-odr0-2 301.00 ( 0.00%) 282.00 ( 6.31%)
Min alloc-odr0-4 247.00 ( 0.00%) 233.00 ( 5.67%)
Min alloc-odr0-8 215.00 ( 0.00%) 203.00 ( 5.58%)
Min alloc-odr0-16 199.00 ( 0.00%) 188.00 ( 5.53%)
Min alloc-odr0-32 191.00 ( 0.00%) 182.00 ( 4.71%)
Min alloc-odr0-64 187.00 ( 0.00%) 177.00 ( 5.35%)
Min alloc-odr0-128 185.00 ( 0.00%) 175.00 ( 5.41%)
Min alloc-odr0-256 193.00 ( 0.00%) 184.00 ( 4.66%)
Min alloc-odr0-512 207.00 ( 0.00%) 197.00 ( 4.83%)
Min alloc-odr0-1024 213.00 ( 0.00%) 203.00 ( 4.69%)
Min alloc-odr0-2048 220.00 ( 0.00%) 209.00 ( 5.00%)
Min alloc-odr0-4096 226.00 ( 0.00%) 214.00 ( 5.31%)
Min alloc-odr0-8192 229.00 ( 0.00%) 218.00 ( 4.80%)
Min alloc-odr0-16384 229.00 ( 0.00%) 219.00 ( 4.37%)
perf indicated that next_zones_zonelist disappeared in the profile and
__next_zones_zonelist did not appear. This is expected as the
micro-benchmark would hit the inlined fast-path every time.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
is_highmem() can be simplified by use of is_highmem_idx(). This patch
removes redundant code and will make it easier to maintain if the zone
policy is changed or a new zone is added.
(akpm: saves me 25 bytes of text per is_highmem() callsite)
Signed-off-by: Chanho Min <chanho.min@lge.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In machines with 140G of memory and enterprise flash storage, we have
seen read and write bursts routinely exceed the kswapd watermarks and
cause thundering herds in direct reclaim. Unfortunately, the only way
to tune kswapd aggressiveness is through adjusting min_free_kbytes - the
system's emergency reserves - which is entirely unrelated to the
system's latency requirements. In order to get kswapd to maintain a
250M buffer of free memory, the emergency reserves need to be set to 1G.
That is a lot of memory wasted for no good reason.
On the other hand, it's reasonable to assume that allocation bursts and
overall allocation concurrency scale with memory capacity, so it makes
sense to make kswapd aggressiveness a function of that as well.
Change the kswapd watermark scale factor from the currently fixed 25% of
the tunable emergency reserve to a tunable 0.1% of memory.
Beyond 1G of memory, this will produce bigger watermark steps than the
current formula in default settings. Ensure that the new formula never
chooses steps smaller than that, i.e. 25% of the emergency reserve.
On a 140G machine, this raises the default watermark steps - the
distance between min and low, and low and high - from 16M to 143M.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Memory compaction can be currently performed in several contexts:
- kswapd balancing a zone after a high-order allocation failure
- direct compaction to satisfy a high-order allocation, including THP
page fault attemps
- khugepaged trying to collapse a hugepage
- manually from /proc
The purpose of compaction is two-fold. The obvious purpose is to
satisfy a (pending or future) high-order allocation, and is easy to
evaluate. The other purpose is to keep overal memory fragmentation low
and help the anti-fragmentation mechanism. The success wrt the latter
purpose is more
The current situation wrt the purposes has a few drawbacks:
- compaction is invoked only when a high-order page or hugepage is not
available (or manually). This might be too late for the purposes of
keeping memory fragmentation low.
- direct compaction increases latency of allocations. Again, it would
be better if compaction was performed asynchronously to keep
fragmentation low, before the allocation itself comes.
- (a special case of the previous) the cost of compaction during THP
page faults can easily offset the benefits of THP.
- kswapd compaction appears to be complex, fragile and not working in
some scenarios. It could also end up compacting for a high-order
allocation request when it should be reclaiming memory for a later
order-0 request.
To improve the situation, we should be able to benefit from an
equivalent of kswapd, but for compaction - i.e. a background thread
which responds to fragmentation and the need for high-order allocations
(including hugepages) somewhat proactively.
One possibility is to extend the responsibilities of kswapd, which could
however complicate its design too much. It should be better to let
kswapd handle reclaim, as order-0 allocations are often more critical
than high-order ones.
Another possibility is to extend khugepaged, but this kthread is a
single instance and tied to THP configs.
This patch goes with the option of a new set of per-node kthreads called
kcompactd, and lays the foundations, without introducing any new
tunables. The lifecycle mimics kswapd kthreads, including the memory
hotplug hooks.
For compaction, kcompactd uses the standard compaction_suitable() and
ompact_finished() criteria and the deferred compaction functionality.
Unlike direct compaction, it uses only sync compaction, as there's no
allocation latency to minimize.
This patch doesn't yet add a call to wakeup_kcompactd. The kswapd
compact/reclaim loop for high-order pages will be replaced by waking up
kcompactd in the next patch with the description of what's wrong with
the old approach.
Waking up of the kcompactd threads is also tied to kswapd activity and
follows these rules:
- we don't want to affect any fastpaths, so wake up kcompactd only from
the slowpath, as it's done for kswapd
- if kswapd is doing reclaim, it's more important than compaction, so
don't invoke kcompactd until kswapd goes to sleep
- the target order used for kswapd is passed to kcompactd
Future possible future uses for kcompactd include the ability to wake up
kcompactd on demand in special situations, such as when hugepages are
not available (currently not done due to __GFP_NO_KSWAPD) or when a
fragmentation event (i.e. __rmqueue_fallback()) occurs. It's also
possible to perform periodic compaction with kcompactd.
[arnd@arndb.de: fix build errors with kcompactd]
[paul.gortmaker@windriver.com: don't use modular references for non modular code]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a performance drop report due to hugepage allocation and in
there half of cpu time are spent on pageblock_pfn_to_page() in
compaction [1].
In that workload, compaction is triggered to make hugepage but most of
pageblocks are un-available for compaction due to pageblock type and
skip bit so compaction usually fails. Most costly operations in this
case is to find valid pageblock while scanning whole zone range. To
check if pageblock is valid to compact, valid pfn within pageblock is
required and we can obtain it by calling pageblock_pfn_to_page(). This
function checks whether pageblock is in a single zone and return valid
pfn if possible. Problem is that we need to check it every time before
scanning pageblock even if we re-visit it and this turns out to be very
expensive in this workload.
Although we have no way to skip this pageblock check in the system where
hole exists at arbitrary position, we can use cached value for zone
continuity and just do pfn_to_page() in the system where hole doesn't
exist. This optimization considerably speeds up in above workload.
Before vs After
Max: 1096 MB/s vs 1325 MB/s
Min: 635 MB/s 1015 MB/s
Avg: 899 MB/s 1194 MB/s
Avg is improved by roughly 30% [2].
[1]: http://www.spinics.net/lists/linux-mm/msg97378.html
[2]: https://lkml.org/lkml/2015/12/9/23
[akpm@linux-foundation.org: don't forget to restore zone->contiguous on error path, per Vlastimil]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reported-by: Aaron Lu <aaron.lu@intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Aaron Lu <aaron.lu@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cache thrash detection (see a528910e12 "mm: thrash detection-based
file cache sizing" for details) currently only works on the system
level, not inside cgroups. Worse, as the refaults are compared to the
global number of active cache, cgroups might wrongfully get all their
refaults activated when their pages are hotter than those of others.
Move the refault machinery from the zone to the lruvec, and then tag
eviction entries with the memcg ID. This makes the thrash detection
work correctly inside cgroups.
[sergey.senozhatsky@gmail.com: do not return from workingset_activation() with locked rcu and page]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The information in /sys/kernel/debug/page_owner includes the migratetype
of the pageblock the page belongs to. This is also checked against the
page's migratetype (as declared by gfp_flags during its allocation), and
the page is reported as Fallback if its migratetype differs from the
pageblock's one. t This is somewhat misleading because in fact fallback
allocation is not the only reason why these two can differ. It also
doesn't direcly provide the page's migratetype, although it's possible
to derive that from the gfp_flags.
It's arguably better to print both page and pageblock's migratetype and
leave the interpretation to the consumer than to suggest fallback
allocation as the only possible reason. While at it, we can print the
migratetypes as string the same way as /proc/pagetypeinfo does, as some
of the numeric values depend on kernel configuration. For that, this
patch moves the migratetype_names array from #ifdef CONFIG_PROC_FS part
of mm/vmstat.c to mm/page_alloc.c and exports it.
With the new format strings for flags, we can now also provide symbolic
page and gfp flags in the /sys/kernel/debug/page_owner file. This
replaces the positional printing of page flags as single letters, which
might have looked nicer, but was limited to a subset of flags, and
required the user to remember the letters.
Example page_owner entry after the patch:
Page allocated via order 0, mask 0x24213ca(GFP_HIGHUSER_MOVABLE|__GFP_COLD|__GFP_NOWARN|__GFP_NORETRY)
PFN 520 type Movable Block 1 type Movable Flags 0xfffff8001006c(referenced|uptodate|lru|active|mappedtodisk)
[<ffffffff811682c4>] __alloc_pages_nodemask+0x134/0x230
[<ffffffff811b4058>] alloc_pages_current+0x88/0x120
[<ffffffff8115e386>] __page_cache_alloc+0xe6/0x120
[<ffffffff8116ba6c>] __do_page_cache_readahead+0xdc/0x240
[<ffffffff8116bd05>] ondemand_readahead+0x135/0x260
[<ffffffff8116bfb1>] page_cache_sync_readahead+0x31/0x50
[<ffffffff81160523>] generic_file_read_iter+0x453/0x760
[<ffffffff811e0d57>] __vfs_read+0xa7/0xd0
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The dirty balance reserve that dirty throttling has to consider is
merely memory not available to userspace allocations. There is nothing
writeback-specific about it. Generalize the name so that it's reusable
outside of that context.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make memmap_valid_within return bool due to this particular function
only using either one or zero as its return value.
No functional change.
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Hardcoding index to zonelists array in gfp_zonelist() is not a good
idea, let's enumerate it to improve readability.
No functional change.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix CONFIG_NUMA=n build]
[n-horiguchi@ah.jp.nec.com: fix warning in comparing enumerator]
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit a0b8cab3b9 ("mm: remove lru parameter from
__pagevec_lru_add and remove parts of pagevec API") there's no
user of this function anymore, so remove it.
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Someone has an 86 column display.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
High-order watermark checking exists for two reasons -- kswapd high-order
awareness and protection for high-order atomic requests. Historically the
kernel depended on MIGRATE_RESERVE to preserve min_free_kbytes as
high-order free pages for as long as possible. This patch introduces
MIGRATE_HIGHATOMIC that reserves pageblocks for high-order atomic
allocations on demand and avoids using those blocks for order-0
allocations. This is more flexible and reliable than MIGRATE_RESERVE was.
A MIGRATE_HIGHORDER pageblock is created when an atomic high-order
allocation request steals a pageblock but limits the total number to 1% of
the zone. Callers that speculatively abuse atomic allocations for
long-lived high-order allocations to access the reserve will quickly fail.
Note that SLUB is currently not such an abuser as it reclaims at least
once. It is possible that the pageblock stolen has few suitable
high-order pages and will need to steal again in the near future but there
would need to be strong justification to search all pageblocks for an
ideal candidate.
The pageblocks are unreserved if an allocation fails after a direct
reclaim attempt.
The watermark checks account for the reserved pageblocks when the
allocation request is not a high-order atomic allocation.
The reserved pageblocks can not be used for order-0 allocations. This may
allow temporary wastage until a failed reclaim reassigns the pageblock.
This is deliberate as the intent of the reservation is to satisfy a
limited number of atomic high-order short-lived requests if the system
requires them.
The stutter benchmark was used to evaluate this but while it was running
there was a systemtap script that randomly allocated between 1 high-order
page and 12.5% of memory's worth of order-3 pages using GFP_ATOMIC. This
is much larger than the potential reserve and it does not attempt to be
realistic. It is intended to stress random high-order allocations from an
unknown source, show that there is a reduction in failures without
introducing an anomaly where atomic allocations are more reliable than
regular allocations. The amount of memory reserved varied throughout the
workload as reserves were created and reclaimed under memory pressure.
The allocation failures once the workload warmed up were as follows;
4.2-rc5-vanilla 70%
4.2-rc5-atomic-reserve 56%
The failure rate was also measured while building multiple kernels. The
failure rate was 14% but is 6% with this patch applied.
Overall, this is a small reduction but the reserves are small relative to
the number of allocation requests. In early versions of the patch, the
failure rate reduced by a much larger amount but that required much larger
reserves and perversely made atomic allocations seem more reliable than
regular allocations.
[yalin.wang2010@gmail.com: fix redundant check and a memory leak]
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: yalin wang <yalin.wang2010@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
MIGRATE_RESERVE preserves an old property of the buddy allocator that
existed prior to fragmentation avoidance -- min_free_kbytes worth of pages
tended to remain contiguous until the only alternative was to fail the
allocation. At the time it was discovered that high-order atomic
allocations relied on this property so MIGRATE_RESERVE was introduced. A
later patch will introduce an alternative MIGRATE_HIGHATOMIC so this patch
deletes MIGRATE_RESERVE and supporting code so it'll be easier to review.
Note that this patch in isolation may look like a false regression if
someone was bisecting high-order atomic allocation failures.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The zonelist cache (zlc) was introduced to skip over zones that were
recently known to be full. This avoided expensive operations such as the
cpuset checks, watermark calculations and zone_reclaim. The situation
today is different and the complexity of zlc is harder to justify.
1) The cpuset checks are no-ops unless a cpuset is active and in general
are a lot cheaper.
2) zone_reclaim is now disabled by default and I suspect that was a large
source of the cost that zlc wanted to avoid. When it is enabled, it's
known to be a major source of stalling when nodes fill up and it's
unwise to hit every other user with the overhead.
3) Watermark checks are expensive to calculate for high-order
allocation requests. Later patches in this series will reduce the cost
of the watermark checking.
4) The most important issue is that in the current implementation it
is possible for a failed THP allocation to mark a zone full for order-0
allocations and cause a fallback to remote nodes.
The last issue could be addressed with additional complexity but as the
benefit of zlc is questionable, it is better to remove it. If stalls due
to zone_reclaim are ever reported then an alternative would be to
introduce deferring logic based on a timeout inside zone_reclaim itself
and leave the page allocator fast paths alone.
The impact on page-allocator microbenchmarks is negligible as they don't
hit the paths where the zlc comes into play. Most page-reclaim related
workloads showed no noticeable difference as a result of the removal.
The impact was noticeable in a workload called "stutter". One part uses a
lot of anonymous memory, a second measures mmap latency and a third copies
a large file. In an ideal world the latency application would not notice
the mmap latency. On a 2-node machine the results of this patch are
stutter
4.3.0-rc1 4.3.0-rc1
baseline nozlc-v4
Min mmap 20.9243 ( 0.00%) 20.7716 ( 0.73%)
1st-qrtle mmap 22.0612 ( 0.00%) 22.0680 ( -0.03%)
2nd-qrtle mmap 22.3291 ( 0.00%) 22.3809 ( -0.23%)
3rd-qrtle mmap 25.2244 ( 0.00%) 25.2396 ( -0.06%)
Max-90% mmap 48.0995 ( 0.00%) 28.3713 ( 41.02%)
Max-93% mmap 52.5557 ( 0.00%) 36.0170 ( 31.47%)
Max-95% mmap 55.8173 ( 0.00%) 47.3163 ( 15.23%)
Max-99% mmap 67.3781 ( 0.00%) 70.1140 ( -4.06%)
Max mmap 24447.6375 ( 0.00%) 12915.1356 ( 47.17%)
Mean mmap 33.7883 ( 0.00%) 27.7944 ( 17.74%)
Best99%Mean mmap 27.7825 ( 0.00%) 25.2767 ( 9.02%)
Best95%Mean mmap 26.3912 ( 0.00%) 23.7994 ( 9.82%)
Best90%Mean mmap 24.9886 ( 0.00%) 23.2251 ( 7.06%)
Best50%Mean mmap 22.0157 ( 0.00%) 22.0261 ( -0.05%)
Best10%Mean mmap 21.6705 ( 0.00%) 21.6083 ( 0.29%)
Best5%Mean mmap 21.5581 ( 0.00%) 21.4611 ( 0.45%)
Best1%Mean mmap 21.3079 ( 0.00%) 21.1631 ( 0.68%)
Note that the maximum stall latency went from 24 seconds to 12 which is
still bad but an improvement. The milage varies considerably 2-node
machine on an earlier test went from 494 seconds to 47 seconds and a
4-node machine that tested an earlier version of this patch went from a
worst case stall time of 6 seconds to 67ms. The nature of the benchmark
is inherently unpredictable as it is hammering the system and the milage
will vary between machines.
There is a secondary impact with potentially more direct reclaim because
zones are now being considered instead of being skipped by zlc. In this
particular test run it did not occur so will not be described. However,
in at least one test the following was observed
1. Direct reclaim rates were higher. This was likely due to direct reclaim
being entered instead of the zlc disabling a zone and busy looping.
Busy looping may have the effect of allowing kswapd to make more
progress and in some cases may be better overall. If this is found then
the correct action is to put direct reclaimers to sleep on a waitqueue
and allow kswapd make forward progress. Busy looping on the zlc is even
worse than when the allocator used to blindly call congestion_wait().
2. There was higher swap activity as direct reclaim was active.
3. Direct reclaim efficiency was lower. This is related to 1 as more
scanning activity also encountered more pages that could not be
immediately reclaimed
In that case, the direct page scan and reclaim rates are noticeable but
it is not considered a problem for a few reasons
1. The test is primarily concerned with latency. The mmap attempts are also
faulted which means there are THP allocation requests. The ZLC could
cause zones to be disabled causing the process to busy loop instead
of reclaiming. This looks like elevated direct reclaim activity but
it's the correct action to take based on what processes requested.
2. The test hammers reclaim and compaction heavily. The number of successful
THP faults is highly variable but affects the reclaim stats. It's not a
realistic or reasonable measure of page reclaim activity.
3. No other page-reclaim intensive workload that was tested showed a problem.
4. If a workload is identified that benefitted from the busy looping then it
should be fixed by having direct reclaimers sleep on a wait queue until
woken by kswapd instead of busy looping. We had this class of problem before
when congestion_waits() with a fixed timeout was a brain damaged decision
but happened to benefit some workloads.
If a workload is identified that relied on the zlc to busy loop then it
should be fixed correctly and have a direct reclaimer sleep on a waitqueue
until woken by kswapd.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch redefines which GFP bits are used for specifying mobility and
the order of the migrate types. Once redefined it's possible to convert
GFP flags to a migrate type with a simple mask and shift. The only
downside is that readers of OOM kill messages and allocation failures may
have been used to the existing values but scripts/gfp-translate will help.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Overall, the intent of this series is to remove the zonelist cache which
was introduced to avoid high overhead in the page allocator. Once this is
done, it is necessary to reduce the cost of watermark checks.
The series starts with minor micro-optimisations.
Next it notes that GFP flags that affect watermark checks are abused.
__GFP_WAIT historically identified callers that could not sleep and could
access reserves. This was later abused to identify callers that simply
prefer to avoid sleeping and have other options. A patch distinguishes
between atomic callers, high-priority callers and those that simply wish
to avoid sleep.
The zonelist cache has been around for a long time but it is of dubious
merit with a lot of complexity and some issues that are explained. The
most important issue is that a failed THP allocation can cause a zone to
be treated as "full". This potentially causes unnecessary stalls, reclaim
activity or remote fallbacks. The issues could be fixed but it's not
worth it. The series places a small number of other micro-optimisations
on top before examining GFP flags watermarks.
High-order watermarks enforcement can cause high-order allocations to fail
even though pages are free. The watermark checks both protect high-order
atomic allocations and make kswapd aware of high-order pages but there is
a much better way that can be handled using migrate types. This series
uses page grouping by mobility to reserve pageblocks for high-order
allocations with the size of the reservation depending on demand. kswapd
awareness is maintained by examining the free lists. By patch 12 in this
series, there are no high-order watermark checks while preserving the
properties that motivated the introduction of the watermark checks.
This patch (of 10):
No user of zone_watermark_ok_safe() specifies alloc_flags. This patch
removes the unnecessary parameter.
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit a2f3aa0257 ("[PATCH] Fix sparsemem on Cell") fixed an oops
experienced on the Cell architecture when init-time functions,
early_*(), are called at runtime by introducing an 'enum memmap_context'
parameter to memmap_init_zone() and init_currently_empty_zone(). This
parameter is intended to be used to tell whether the call of these two
functions is being made on behalf of a hotplug event, or happening at
boot-time. However, init_currently_empty_zone() does not use this
parameter at all, so remove it.
Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1/ Introduce ZONE_DEVICE and devm_memremap_pages() as a generic
mechanism for adding device-driver-discovered memory regions to the
kernel's direct map. This facility is used by the pmem driver to
enable pfn_to_page() operations on the page frames returned by DAX
('direct_access' in 'struct block_device_operations'). For now, the
'memmap' allocation for these "device" pages comes from "System
RAM". Support for allocating the memmap from device memory will
arrive in a later kernel.
2/ Introduce memremap() to replace usages of ioremap_cache() and
ioremap_wt(). memremap() drops the __iomem annotation for these
mappings to memory that do not have i/o side effects. The
replacement of ioremap_cache() with memremap() is limited to the
pmem driver to ease merging the api change in v4.3. Completion of
the conversion is targeted for v4.4.
3/ Similar to the usage of memcpy_to_pmem() + wmb_pmem() in the pmem
driver, update the VFS DAX implementation and PMEM api to provide
persistence guarantees for kernel operations on a DAX mapping.
4/ Convert the ACPI NFIT 'BLK' driver to map the block apertures as
cacheable to improve performance.
5/ Miscellaneous updates and fixes to libnvdimm including support
for issuing "address range scrub" commands, clarifying the optimal
'sector size' of pmem devices, a clarification of the usage of the
ACPI '_STA' (status) property for DIMM devices, and other minor
fixes.
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Merge tag 'libnvdimm-for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull libnvdimm updates from Dan Williams:
"This update has successfully completed a 0day-kbuild run and has
appeared in a linux-next release. The changes outside of the typical
drivers/nvdimm/ and drivers/acpi/nfit.[ch] paths are related to the
removal of IORESOURCE_CACHEABLE, the introduction of memremap(), and
the introduction of ZONE_DEVICE + devm_memremap_pages().
Summary:
- Introduce ZONE_DEVICE and devm_memremap_pages() as a generic
mechanism for adding device-driver-discovered memory regions to the
kernel's direct map.
This facility is used by the pmem driver to enable pfn_to_page()
operations on the page frames returned by DAX ('direct_access' in
'struct block_device_operations').
For now, the 'memmap' allocation for these "device" pages comes
from "System RAM". Support for allocating the memmap from device
memory will arrive in a later kernel.
- Introduce memremap() to replace usages of ioremap_cache() and
ioremap_wt(). memremap() drops the __iomem annotation for these
mappings to memory that do not have i/o side effects. The
replacement of ioremap_cache() with memremap() is limited to the
pmem driver to ease merging the api change in v4.3.
Completion of the conversion is targeted for v4.4.
- Similar to the usage of memcpy_to_pmem() + wmb_pmem() in the pmem
driver, update the VFS DAX implementation and PMEM api to provide
persistence guarantees for kernel operations on a DAX mapping.
- Convert the ACPI NFIT 'BLK' driver to map the block apertures as
cacheable to improve performance.
- Miscellaneous updates and fixes to libnvdimm including support for
issuing "address range scrub" commands, clarifying the optimal
'sector size' of pmem devices, a clarification of the usage of the
ACPI '_STA' (status) property for DIMM devices, and other minor
fixes"
* tag 'libnvdimm-for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (34 commits)
libnvdimm, pmem: direct map legacy pmem by default
libnvdimm, pmem: 'struct page' for pmem
libnvdimm, pfn: 'struct page' provider infrastructure
x86, pmem: clarify that ARCH_HAS_PMEM_API implies PMEM mapped WB
add devm_memremap_pages
mm: ZONE_DEVICE for "device memory"
mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h
dax: drop size parameter to ->direct_access()
nd_blk: change aperture mapping from WC to WB
nvdimm: change to use generic kvfree()
pmem, dax: have direct_access use __pmem annotation
dax: update I/O path to do proper PMEM flushing
pmem: add copy_from_iter_pmem() and clear_pmem()
pmem, x86: clean up conditional pmem includes
pmem: remove layer when calling arch_has_wmb_pmem()
pmem, x86: move x86 PMEM API to new pmem.h header
libnvdimm, e820: make CONFIG_X86_PMEM_LEGACY a tristate option
pmem: switch to devm_ allocations
devres: add devm_memremap
libnvdimm, btt: write and validate parent_uuid
...
struct node_active_region is not used anymore. Remove it.
Signed-off-by: minkyung88.kim <minkyung88.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
While pmem is usable as a block device or via DAX mappings to userspace
there are several usage scenarios that can not target pmem due to its
lack of struct page coverage. In preparation for "hot plugging" pmem
into the vmemmap add ZONE_DEVICE as a new zone to tag these pages
separately from the ones that are subject to standard page allocations.
Importantly "device memory" can be removed at will by userspace
unbinding the driver of the device.
Having a separate zone prevents allocation and otherwise marks these
pages that are distinct from typical uniform memory. Device memory has
different lifetime and performance characteristics than RAM. However,
since we have run out of ZONES_SHIFT bits this functionality currently
depends on sacrificing ZONE_DMA.
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Jerome Glisse <j.glisse@gmail.com>
[hch: various simplifications in the arch interface]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This patch initalises all low memory struct pages and 2G of the highest
zone on each node during memory initialisation if
CONFIG_DEFERRED_STRUCT_PAGE_INIT is set. That config option cannot be set
but will be available in a later patch. Parallel initialisation of struct
page depends on some features from memory hotplug and it is necessary to
alter alter section annotations.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Nate Zimmer <nzimmer@sgi.com>
Tested-by: Waiman Long <waiman.long@hp.com>
Tested-by: Daniel J Blueman <daniel@numascale.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Nate Zimmer <nzimmer@sgi.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Scott Norton <scott.norton@hp.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
early_pfn_in_nid() and meminit_pfn_in_nid() are small functions that are
unnecessarily visible outside memory initialisation. As well as
unnecessary visibility, it's unnecessary function call overhead when
initialising pages. This patch moves the helpers inline.
[akpm@linux-foundation.org: fix build]
[mhocko@suse.cz: fix build]
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Nate Zimmer <nzimmer@sgi.com>
Tested-by: Waiman Long <waiman.long@hp.com>
Tested-by: Daniel J Blueman <daniel@numascale.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Nate Zimmer <nzimmer@sgi.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Scott Norton <scott.norton@hp.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__early_pfn_to_nid() use static variables to cache recent lookups as
memblock lookups are very expensive but it assumes that memory
initialisation is single-threaded. Parallel initialisation of struct
pages will break that assumption so this patch makes __early_pfn_to_nid()
SMP-safe by requiring the caller to cache recent search information.
early_pfn_to_nid() keeps the same interface but is only safe to use early
in boot due to the use of a global static variable. meminit_pfn_in_nid()
is an SMP-safe version that callers must maintain their own state for.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Nate Zimmer <nzimmer@sgi.com>
Tested-by: Waiman Long <waiman.long@hp.com>
Tested-by: Daniel J Blueman <daniel@numascale.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Nate Zimmer <nzimmer@sgi.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Scott Norton <scott.norton@hp.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All callers of zone_movable_is_highmem are under #ifdef CONFIG_HIGHMEM,
so the else branch return 0 is not needed.
Signed-off-by: Zhang Zhen <zhenzhang.zhang@huawei.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Huang Ying reported the following problem due to commit 3484b2de94 ("mm:
rearrange zone fields into read-only, page alloc, statistics and page
reclaim lines") from the Intel performance tests
24b7e5819a3484b2de94
---------------- --------------------------
%stddev %change %stddev
\ | \
152288 \261 0% -46.2% 81911 \261 0% aim7.jobs-per-min
237 \261 0% +85.6% 440 \261 0% aim7.time.elapsed_time
237 \261 0% +85.6% 440 \261 0% aim7.time.elapsed_time.max
25026 \261 0% +70.7% 42712 \261 0% aim7.time.system_time
2186645 \261 5% +32.0% 2885949 \261 4% aim7.time.voluntary_context_switches
4576561 \261 1% +24.9% 5715773 \261 0% aim7.time.involuntary_context_switches
The problem is specific to very large machines under stress. It was not
reproducible with the machines I had used to justify the original patch
because large numbers of CPUs are required. When pressure is high enough,
the cache line is bouncing between CPUs trying to acquire the lock and the
holder of the lock adjusting free lists. The intention was that the
acquirer of the lock would automatically have the cache line holding the
free lists but according to Huang, this is not a universal win.
One possibility is to move the zone lock to its own cache line but it
increases the size of the zone. This patch moves the lock to the other
end of the free lists where they do not contend under high pressure. It
does mean the page allocator paths now require more cache lines but Huang
reports that it restores performance to previous levels on large machines
%stddev %change %stddev
\ | \
84568 \261 1% +94.3% 164280 \261 1% aim7.jobs-per-min
2881944 \261 2% -35.1% 1870386 \261 8% aim7.time.voluntary_context_switches
681 \261 1% -3.4% 658 \261 0% aim7.time.user_time
5538139 \261 0% -12.1% 4867884 \261 0% aim7.time.involuntary_context_switches
44174 \261 1% -46.0% 23848 \261 1% aim7.time.system_time
426 \261 1% -48.4% 219 \261 1% aim7.time.elapsed_time
426 \261 1% -48.4% 219 \261 1% aim7.time.elapsed_time.max
468 \261 1% -43.1% 266 \261 2% uptime.boot
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-by: Huang Ying <ying.huang@intel.com>
Tested-by: Huang Ying <ying.huang@intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
next_zones_zonelist() returns a zoneref pointer, as well as a zone pointer
via extra parameter. Since the latter can be trivially obtained by
dereferencing the former, the overhead of the extra parameter is
unjustified.
This patch thus removes the zone parameter from next_zones_zonelist().
Both callers happen to be in the same header file, so it's simple to add
the zoneref dereference inline. We save some bytes of code size.
add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-105 (-105)
function old new delta
nr_free_zone_pages 129 115 -14
__alloc_pages_nodemask 2300 2285 -15
get_page_from_freelist 2652 2576 -76
add/remove: 0/0 grow/shrink: 1/0 up/down: 10/0 (10)
function old new delta
try_to_compact_pages 569 579 +10
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Found it when I want to jump to the definition of MIGRATE_RESERVE ctags.
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When we debug something, we'd like to insert some information to every
page. For this purpose, we sometimes modify struct page itself. But,
this has drawbacks. First, it requires re-compile. This makes us
hesitate to use the powerful debug feature so development process is
slowed down. And, second, sometimes it is impossible to rebuild the
kernel due to third party module dependency. At third, system behaviour
would be largely different after re-compile, because it changes size of
struct page greatly and this structure is accessed by every part of
kernel. Keeping this as it is would be better to reproduce errornous
situation.
This feature is intended to overcome above mentioned problems. This
feature allocates memory for extended data per page in certain place
rather than the struct page itself. This memory can be accessed by the
accessor functions provided by this code. During the boot process, it
checks whether allocation of huge chunk of memory is needed or not. If
not, it avoids allocating memory at all. With this advantage, we can
include this feature into the kernel in default and can avoid rebuild and
solve related problems.
Until now, memcg uses this technique. But, now, memcg decides to embed
their variable to struct page itself and it's code to extend struct page
has been removed. I'd like to use this code to develop debug feature, so
this patch resurrect it.
To help these things to work well, this patch introduces two callbacks for
clients. One is the need callback which is mandatory if user wants to
avoid useless memory allocation at boot-time. The other is optional, init
callback, which is used to do proper initialization after memory is
allocated. Detailed explanation about purpose of these functions is in
code comment. Please refer it.
Others are completely same with previous extension code in memcg.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Jungsoo Son <jungsoo.son@lge.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Memory cgroups used to have 5 per-page pointers. To allow users to
disable that amount of overhead during runtime, those pointers were
allocated in a separate array, with a translation layer between them and
struct page.
There is now only one page pointer remaining: the memcg pointer, that
indicates which cgroup the page is associated with when charged. The
complexity of runtime allocation and the runtime translation overhead is
no longer justified to save that *potential* 0.19% of memory. With
CONFIG_SLUB, page->mem_cgroup actually sits in the doubleword padding
after the page->private member and doesn't even increase struct page,
and then this patch actually saves space. Remaining users that care can
still compile their kernels without CONFIG_MEMCG.
text data bss dec hex filename
8828345 1725264 983040 11536649 b00909 vmlinux.old
8827425 1725264 966656 11519345 afc571 vmlinux.new
[mhocko@suse.cz: update Documentation/cgroups/memory.txt]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Before describing bugs itself, I first explain definition of freepage.
1. pages on buddy list are counted as freepage.
2. pages on isolate migratetype buddy list are *not* counted as freepage.
3. pages on cma buddy list are counted as CMA freepage, too.
Now, I describe problems and related patch.
Patch 1: There is race conditions on getting pageblock migratetype that
it results in misplacement of freepages on buddy list, incorrect
freepage count and un-availability of freepage.
Patch 2: Freepages on pcp list could have stale cached information to
determine migratetype of buddy list to go. This causes misplacement of
freepages on buddy list and incorrect freepage count.
Patch 4: Merging between freepages on different migratetype of
pageblocks will cause freepages accouting problem. This patch fixes it.
Without patchset [3], above problem doesn't happens on my CMA allocation
test, because CMA reserved pages aren't used at all. So there is no
chance for above race.
With patchset [3], I did simple CMA allocation test and get below
result:
- Virtual machine, 4 cpus, 1024 MB memory, 256 MB CMA reservation
- run kernel build (make -j16) on background
- 30 times CMA allocation(8MB * 30 = 240MB) attempts in 5 sec interval
- Result: more than 5000 freepage count are missed
With patchset [3] and this patchset, I found that no freepage count are
missed so that I conclude that problems are solved.
On my simple memory offlining test, these problems also occur on that
environment, too.
This patch (of 4):
There are two paths to reach core free function of buddy allocator,
__free_one_page(), one is free_one_page()->__free_one_page() and the
other is free_hot_cold_page()->free_pcppages_bulk()->__free_one_page().
Each paths has race condition causing serious problems. At first, this
patch is focused on first type of freepath. And then, following patch
will solve the problem in second type of freepath.
In the first type of freepath, we got migratetype of freeing page
without holding the zone lock, so it could be racy. There are two cases
of this race.
1. pages are added to isolate buddy list after restoring orignal
migratetype
CPU1 CPU2
get migratetype => return MIGRATE_ISOLATE
call free_one_page() with MIGRATE_ISOLATE
grab the zone lock
unisolate pageblock
release the zone lock
grab the zone lock
call __free_one_page() with MIGRATE_ISOLATE
freepage go into isolate buddy list,
although pageblock is already unisolated
This may cause two problems. One is that we can't use this page anymore
until next isolation attempt of this pageblock, because freepage is on
isolate buddy list. The other is that freepage accouting could be wrong
due to merging between different buddy list. Freepages on isolate buddy
list aren't counted as freepage, but ones on normal buddy list are
counted as freepage. If merge happens, buddy freepage on normal buddy
list is inevitably moved to isolate buddy list without any consideration
of freepage accouting so it could be incorrect.
2. pages are added to normal buddy list while pageblock is isolated.
It is similar with above case.
This also may cause two problems. One is that we can't keep these
freepages from being allocated. Although this pageblock is isolated,
freepage would be added to normal buddy list so that it could be
allocated without any restriction. And the other problem is same as
case 1, that it, incorrect freepage accouting.
This race condition would be prevented by checking migratetype again
with holding the zone lock. Because it is somewhat heavy operation and
it isn't needed in common case, we want to avoid rechecking as much as
possible. So this patch introduce new variable, nr_isolate_pageblock in
struct zone to check if there is isolated pageblock. With this, we can
avoid to re-check migratetype in common case and do it only if there is
isolated pageblock or migratetype is MIGRATE_ISOLATE. This solve above
mentioned problems.
Changes from v3:
Add one more check in free_one_page() that checks whether migratetype is
MIGRATE_ISOLATE or not. Without this, abovementioned case 1 could happens.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Heesub Shin <heesub.shin@samsung.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Ritesh Harjani <ritesh.list@gmail.com>
Cc: Gioh Kim <gioh.kim@lge.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Page reclaim tests zone_is_reclaim_dirty(), but the site that actually
sets this state does zone_set_flag(zone, ZONE_TAIL_LRU_DIRTY), sending the
reader through layers indirection just to track down a simple bit.
Remove all zone flag wrappers and just use bitops against zone->flags
directly. It's just as readable and the lines are barely any longer.
Also rename ZONE_TAIL_LRU_DIRTY to ZONE_DIRTY to match ZONE_WRITEBACK, and
remove the zone_flags_t typedef.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The fair zone allocation policy round-robins allocations between zones
within a node to avoid age inversion problems during reclaim. If the
first allocation fails, the batch counts are reset and a second attempt
made before entering the slow path.
One assumption made with this scheme is that batches expire at roughly
the same time and the resets each time are justified. This assumption
does not hold when zones reach their low watermark as the batches will
be consumed at uneven rates. Allocation failure due to watermark
depletion result in additional zonelist scans for the reset and another
watermark check before hitting the slowpath.
On UMA, the benefit is negligible -- around 0.25%. On 4-socket NUMA
machine it's variable due to the variability of measuring overhead with
the vmstat changes. The system CPU overhead comparison looks like
3.16.0-rc3 3.16.0-rc3 3.16.0-rc3
vanilla vmstat-v5 lowercost-v5
User 746.94 774.56 802.00
System 65336.22 32847.27 40852.33
Elapsed 27553.52 27415.04 27368.46
However it is worth noting that the overall benchmark still completed
faster and intuitively it makes sense to take as few passes as possible
through the zonelists.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
zone->pages_scanned is a write-intensive cache line during page reclaim
and it's also updated during page free. Move the counter into vmstat to
take advantage of the per-cpu updates and do not update it in the free
paths unless necessary.
On a small UMA machine running tiobench the difference is marginal. On
a 4-node machine the overhead is more noticable. Note that automatic
NUMA balancing was disabled for this test as otherwise the system CPU
overhead is unpredictable.
3.16.0-rc3 3.16.0-rc3 3.16.0-rc3
vanillarearrange-v5 vmstat-v5
User 746.94 759.78 774.56
System 65336.22 58350.98 32847.27
Elapsed 27553.52 27282.02 27415.04
Note that the overhead reduction will vary depending on where exactly
pages are allocated and freed.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The arrangement of struct zone has changed over time and now it has
reached the point where there is some inappropriate sharing going on.
On x86-64 for example
o The zone->node field is shared with the zone lock and zone->node is
accessed frequently from the page allocator due to the fair zone
allocation policy.
o span_seqlock is almost never used by shares a line with free_area
o Some zone statistics share a cache line with the LRU lock so
reclaim-intensive and allocator-intensive workloads can bounce the cache
line on a stat update
This patch rearranges struct zone to put read-only and read-mostly
fields together and then splits the page allocator intensive fields, the
zone statistics and the page reclaim intensive fields into their own
cache lines. Note that the type of lowmem_reserve changes due to the
watermark calculations being signed and avoiding a signed/unsigned
conversion there.
On the test configuration I used the overall size of struct zone shrunk
by one cache line. On smaller machines, this is not likely to be
noticable. However, on a 4-node NUMA machine running tiobench the
system CPU overhead is reduced by this patch.
3.16.0-rc3 3.16.0-rc3
vanillarearrange-v5r9
User 746.94 759.78
System 65336.22 58350.98
Elapsed 27553.52 27282.02
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In original code, zone_movable_is_highmem() assumes ZONE_MOVABLE not
highmem if CONFIG_HAVE_MEMBLOCK_NODE_MAP is not set. In online_pages,
it extracts pages from the previous zone before ZONE_MOVABLE. Which is
logically inconsistent:
If HAVE_MEMBLOCK_NODE_MAP is turned off but HIGHMEM is on,
zone_movable_is_highmem() makes movable zone not highmem, but
online_pages() extracts pages from ZONE_HIGHMEM.
This inconsistency doesn't cause real problem currently, because all
architectures support online_pages also have HAVE_MEMBLOCK_NODE_MAP.
However, fixing it makes code clear, and also helps futher coding.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Zhang Zhen <zhangzhen@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
X86 prefers the use of unsigned types for iterators and there is a
tendency to mix whether a signed or unsigned type if used for page order.
This converts a number of sites in mm/page_alloc.c to use unsigned int for
order where possible.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The test_bit operations in get/set pageblock flags are expensive. This
patch reads the bitmap on a word basis and use shifts and masks to isolate
the bits of interest. Similarly masks are used to set a local copy of the
bitmap and then use cmpxchg to update the bitmap if there have been no
other changes made in parallel.
In a test running dd onto tmpfs the overhead of the pageblock-related
functions went from 1.27% in profiles to 0.5%.
In addition to the performance benefits, this patch closes races that are
possible between:
a) get_ and set_pageblock_migratetype(), where get_pageblock_migratetype()
reads part of the bits before and other part of the bits after
set_pageblock_migratetype() has updated them.
b) set_pageblock_migratetype() and set_pageblock_skip(), where the non-atomic
read-modify-update set bit operation in set_pageblock_skip() will cause
lost updates to some bits changed in the set_pageblock_migratetype().
Joonsoo Kim first reported the case a) via code inspection. Vlastimil
Babka's testing with a debug patch showed that either a) or b) occurs
roughly once per mmtests' stress-highalloc benchmark (although not
necessarily in the same pageblock). Furthermore during development of
unrelated compaction patches, it was observed that frequent calls to
{start,undo}_isolate_page_range() the race occurs several thousands of
times and has resulted in NULL pointer dereferences in move_freepages()
and free_one_page() in places where free_list[migratetype] is
manipulated by e.g. list_move(). Further debugging confirmed that
migratetype had invalid value of 6, causing out of bounds access to the
free_list array.
That confirmed that the race exist, although it may be extremely rare,
and currently only fatal where page isolation is performed due to
memory hot remove. Races on pageblocks being updated by
set_pageblock_migratetype(), where both old and new migratetype are
lower MIGRATE_RESERVE, currently cannot result in an invalid value
being observed, although theoretically they may still lead to
unexpected creation or destruction of MIGRATE_RESERVE pageblocks.
Furthermore, things could get suddenly worse when memory isolation is
used more, or when new migratetypes are added.
After this patch, the race has no longer been observed in testing.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reported-and-tested-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Each zone has a cached migration scanner pfn for memory compaction so that
subsequent calls to memory compaction can start where the previous call
left off.
Currently, the compaction migration scanner only updates the per-zone
cached pfn when pageblocks were not skipped for async compaction. This
creates a dependency on calling sync compaction to avoid having subsequent
calls to async compaction from scanning an enormous amount of non-MOVABLE
pageblocks each time it is called. On large machines, this could be
potentially very expensive.
This patch adds a per-zone cached migration scanner pfn only for async
compaction. It is updated everytime a pageblock has been scanned in its
entirety and when no pages from it were successfully isolated. The cached
migration scanner pfn for sync compaction is updated only when called for
sync compaction.
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kmem_cache_{create,destroy,shrink} need to get a stable value of
cpu/node online mask, because they init/destroy/access per-cpu/node
kmem_cache parts, which can be allocated or destroyed on cpu/mem
hotplug. To protect against cpu hotplug, these functions use
{get,put}_online_cpus. However, they do nothing to synchronize with
memory hotplug - taking the slab_mutex does not eliminate the
possibility of race as described in patch 2.
What we need there is something like get_online_cpus, but for memory.
We already have lock_memory_hotplug, which serves for the purpose, but
it's a bit of a hammer right now, because it's backed by a mutex. As a
result, it imposes some limitations to locking order, which are not
desirable, and can't be used just like get_online_cpus. That's why in
patch 1 I substitute it with get/put_online_mems, which work exactly
like get/put_online_cpus except they block not cpu, but memory hotplug.
[ v1 can be found at https://lkml.org/lkml/2014/4/6/68. I NAK'ed it by
myself, because it used an rw semaphore for get/put_online_mems,
making them dead lock prune. ]
This patch (of 2):
{un}lock_memory_hotplug, which is used to synchronize against memory
hotplug, is currently backed by a mutex, which makes it a bit of a
hammer - threads that only want to get a stable value of online nodes
mask won't be able to proceed concurrently. Also, it imposes some
strong locking ordering rules on it, which narrows down the set of its
usage scenarios.
This patch introduces get/put_online_mems, which are the same as
get/put_online_cpus, but for memory hotplug, i.e. executing a code
inside a get/put_online_mems section will guarantee a stable value of
online nodes, present pages, etc.
lock_memory_hotplug()/unlock_memory_hotplug() are removed altogether.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
pgdat->reclaim_nodes tracks if a remote node is allowed to be reclaimed
by zone_reclaim due to its distance. As it is expected that
zone_reclaim_mode will be rarely enabled it is unreasonable for all
machines to take a penalty. Fortunately, the zone_reclaim_mode() path
is already slow and it is the path that takes the hit.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previously, page cache radix tree nodes were freed after reclaim emptied
out their page pointers. But now reclaim stores shadow entries in their
place, which are only reclaimed when the inodes themselves are
reclaimed. This is problematic for bigger files that are still in use
after they have a significant amount of their cache reclaimed, without
any of those pages actually refaulting. The shadow entries will just
sit there and waste memory. In the worst case, the shadow entries will
accumulate until the machine runs out of memory.
To get this under control, the VM will track radix tree nodes
exclusively containing shadow entries on a per-NUMA node list. Per-NUMA
rather than global because we expect the radix tree nodes themselves to
be allocated node-locally and we want to reduce cross-node references of
otherwise independent cache workloads. A simple shrinker will then
reclaim these nodes on memory pressure.
A few things need to be stored in the radix tree node to implement the
shadow node LRU and allow tree deletions coming from the list:
1. There is no index available that would describe the reverse path
from the node up to the tree root, which is needed to perform a
deletion. To solve this, encode in each node its offset inside the
parent. This can be stored in the unused upper bits of the same
member that stores the node's height at no extra space cost.
2. The number of shadow entries needs to be counted in addition to the
regular entries, to quickly detect when the node is ready to go to
the shadow node LRU list. The current entry count is an unsigned
int but the maximum number of entries is 64, so a shadow counter
can easily be stored in the unused upper bits.
3. Tree modification needs tree lock and tree root, which are located
in the address space, so store an address_space backpointer in the
node. The parent pointer of the node is in a union with the 2-word
rcu_head, so the backpointer comes at no extra cost as well.
4. The node needs to be linked to an LRU list, which requires a list
head inside the node. This does increase the size of the node, but
it does not change the number of objects that fit into a slab page.
[akpm@linux-foundation.org: export the right function]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bob Liu <bob.liu@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Metin Doslu <metin@citusdata.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ozgun Erdogan <ozgun@citusdata.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The VM maintains cached filesystem pages on two types of lists. One
list holds the pages recently faulted into the cache, the other list
holds pages that have been referenced repeatedly on that first list.
The idea is to prefer reclaiming young pages over those that have shown
to benefit from caching in the past. We call the recently usedbut
ultimately was not significantly better than a FIFO policy and still
thrashed cache based on eviction speed, rather than actual demand for
cache.
This patch solves one half of the problem by decoupling the ability to
detect working set changes from the inactive list size. By maintaining
a history of recently evicted file pages it can detect frequently used
pages with an arbitrarily small inactive list size, and subsequently
apply pressure on the active list based on actual demand for cache, not
just overall eviction speed.
Every zone maintains a counter that tracks inactive list aging speed.
When a page is evicted, a snapshot of this counter is stored in the
now-empty page cache radix tree slot. On refault, the minimum access
distance of the page can be assessed, to evaluate whether the page
should be part of the active list or not.
This fixes the VM's blindness towards working set changes in excess of
the inactive list. And it's the foundation to further improve the
protection ability and reduce the minimum inactive list size of 50%.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Luigi Semenzato <semenzato@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Metin Doslu <metin@citusdata.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ozgun Erdogan <ozgun@citusdata.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <klamm@yandex-team.ru>
Cc: Ryan Mallon <rmallon@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
GFP_THISNODE is for callers that implement their own clever fallback to
remote nodes. It restricts the allocation to the specified node and
does not invoke reclaim, assuming that the caller will take care of it
when the fallback fails, e.g. through a subsequent allocation request
without GFP_THISNODE set.
However, many current GFP_THISNODE users only want the node exclusive
aspect of the flag, without actually implementing their own fallback or
triggering reclaim if necessary. This results in things like page
migration failing prematurely even when there is easily reclaimable
memory available, unless kswapd happens to be running already or a
concurrent allocation attempt triggers the necessary reclaim.
Convert all callsites that don't implement their own fallback strategy
to __GFP_THISNODE. This restricts the allocation a single node too, but
at the same time allows the allocator to enter the slowpath, wake
kswapd, and invoke direct reclaim if necessary, to make the allocation
happen when memory is full.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Jan Stancek <jstancek@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
NUMA migrate rate limiting protects a migration counter and window using
a lock but in some cases this can be a contended lock. It is not
critical that the number of pages be perfect, lost updates are
acceptable. Reduce the importance of this lock.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Alex Thorlton <athorlton@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yasuaki Ishimatsu reported memory hot-add spent more than 5 _hours_ on
9TB memory machine since onlining memory sections is too slow. And we
found out setup_zone_migrate_reserve spent >90% of the time.
The problem is, setup_zone_migrate_reserve scans all pageblocks
unconditionally, but it is only necessary if the number of reserved
block was reduced (i.e. memory hot remove).
Moreover, maximum MIGRATE_RESERVE per zone is currently 2. It means
that the number of reserved pageblocks is almost always unchanged.
This patch adds zone->nr_migrate_reserve_block to maintain the number of
MIGRATE_RESERVE pageblocks and it reduces the overhead of
setup_zone_migrate_reserve dramatically. The following table shows time
of onlining a memory section.
Amount of memory | 128GB | 192GB | 256GB|
---------------------------------------------
linux-3.12 | 23.9 | 31.4 | 44.5 |
This patch | 8.3 | 8.3 | 8.6 |
Mel's proposal patch | 10.9 | 19.2 | 31.3 |
---------------------------------------------
(millisecond)
128GB : 4 nodes and each node has 32GB of memory
192GB : 6 nodes and each node has 32GB of memory
256GB : 8 nodes and each node has 32GB of memory
(*1) Mel proposed his idea by the following threads.
https://lkml.org/lkml/2013/10/30/272
[akpm@linux-foundation.org: tweak comment]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Reported-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Tested-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch is based on KOSAKI's work and I add a little more description,
please refer https://lkml.org/lkml/2012/6/14/74.
Currently, I found system can enter a state that there are lots of free
pages in a zone but only order-0 and order-1 pages which means the zone is
heavily fragmented, then high order allocation could make direct reclaim
path's long stall(ex, 60 seconds) especially in no swap and no compaciton
enviroment. This problem happened on v3.4, but it seems issue still lives
in current tree, the reason is do_try_to_free_pages enter live lock:
kswapd will go to sleep if the zones have been fully scanned and are still
not balanced. As kswapd thinks there's little point trying all over again
to avoid infinite loop. Instead it changes order from high-order to
0-order because kswapd think order-0 is the most important. Look at
73ce02e9 in detail. If watermarks are ok, kswapd will go back to sleep
and may leave zone->all_unreclaimable =3D 0. It assume high-order users
can still perform direct reclaim if they wish.
Direct reclaim continue to reclaim for a high order which is not a
COSTLY_ORDER without oom-killer until kswapd turn on
zone->all_unreclaimble= . This is because to avoid too early oom-kill.
So it means direct_reclaim depends on kswapd to break this loop.
In worst case, direct-reclaim may continue to page reclaim forever when
kswapd sleeps forever until someone like watchdog detect and finally kill
the process. As described in:
http://thread.gmane.org/gmane.linux.kernel.mm/103737
We can't turn on zone->all_unreclaimable from direct reclaim path because
direct reclaim path don't take any lock and this way is racy. Thus this
patch removes zone->all_unreclaimable field completely and recalculates
zone reclaimable state every time.
Note: we can't take the idea that direct-reclaim see zone->pages_scanned
directly and kswapd continue to use zone->all_unreclaimable. Because, it
is racy. commit 929bea7c71 (vmscan: all_unreclaimable() use
zone->all_unreclaimable as a name) describes the detail.
[akpm@linux-foundation.org: uninline zone_reclaimable_pages() and zone_reclaimable()]
Cc: Aaditya Kumar <aaditya.kumar.30@gmail.com>
Cc: Ying Han <yinghan@google.com>
Cc: Nick Piggin <npiggin@gmail.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Bob Liu <lliubbo@gmail.com>
Cc: Neil Zhang <zhangwm@marvell.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Lisa Du <cldu@marvell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Each zone that holds userspace pages of one workload must be aged at a
speed proportional to the zone size. Otherwise, the time an individual
page gets to stay in memory depends on the zone it happened to be
allocated in. Asymmetry in the zone aging creates rather unpredictable
aging behavior and results in the wrong pages being reclaimed, activated
etc.
But exactly this happens right now because of the way the page allocator
and kswapd interact. The page allocator uses per-node lists of all zones
in the system, ordered by preference, when allocating a new page. When
the first iteration does not yield any results, kswapd is woken up and the
allocator retries. Due to the way kswapd reclaims zones below the high
watermark while a zone can be allocated from when it is above the low
watermark, the allocator may keep kswapd running while kswapd reclaim
ensures that the page allocator can keep allocating from the first zone in
the zonelist for extended periods of time. Meanwhile the other zones
rarely see new allocations and thus get aged much slower in comparison.
The result is that the occasional page placed in lower zones gets
relatively more time in memory, even gets promoted to the active list
after its peers have long been evicted. Meanwhile, the bulk of the
working set may be thrashing on the preferred zone even though there may
be significant amounts of memory available in the lower zones.
Even the most basic test -- repeatedly reading a file slightly bigger than
memory -- shows how broken the zone aging is. In this scenario, no single
page should be able stay in memory long enough to get referenced twice and
activated, but activation happens in spades:
$ grep active_file /proc/zoneinfo
nr_inactive_file 0
nr_active_file 0
nr_inactive_file 0
nr_active_file 8
nr_inactive_file 1582
nr_active_file 11994
$ cat data data data data >/dev/null
$ grep active_file /proc/zoneinfo
nr_inactive_file 0
nr_active_file 70
nr_inactive_file 258753
nr_active_file 443214
nr_inactive_file 149793
nr_active_file 12021
Fix this with a very simple round robin allocator. Each zone is allowed a
batch of allocations that is proportional to the zone's size, after which
it is treated as full. The batch counters are reset when all zones have
been tried and the allocator enters the slowpath and kicks off kswapd
reclaim. Allocation and reclaim is now fairly spread out to all
available/allowable zones:
$ grep active_file /proc/zoneinfo
nr_inactive_file 0
nr_active_file 0
nr_inactive_file 174
nr_active_file 4865
nr_inactive_file 53
nr_active_file 860
$ cat data data data data >/dev/null
$ grep active_file /proc/zoneinfo
nr_inactive_file 0
nr_active_file 0
nr_inactive_file 666622
nr_active_file 4988
nr_inactive_file 190969
nr_active_file 937
When zone_reclaim_mode is enabled, allocations will now spread out to all
zones on the local node, not just the first preferred zone (which on a 4G
node might be a tiny Normal zone).
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Paul Bolle <paul.bollee@gmail.com>
Cc: Zlatko Calusic <zcalusic@bitsync.net>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These functions are nowhere used, so remove them.
Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Instead of leaving a hidden trap for the next person who comes along and
wants to add something to mem_section, add a big fat warning about it
needing to be a power-of-2, and insert a BUILD_BUG_ON() in sparse_init()
to catch mistakes.
Right now non-power-of-2 mem_sections cause a number of WARNs at boot
(which don't clearly point to the size of mem_section as an issue), but
the system limps on (temporarily, at least).
This is based upon Dave Hansen's earlier RFC where he ran into the same
issue:
"sparsemem: fix boot when SECTIONS_PER_ROOT is not power-of-2"
http://lkml.indiana.edu/hypermail/linux/kernel/1205.2/03077.html
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently lock_memory_hotplug()/unlock_memory_hotplug() are used to
protect totalram_pages and zone->managed_pages. Other than the memory
hotplug driver, totalram_pages and zone->managed_pages may also be
modified at runtime by other drivers, such as Xen balloon,
virtio_balloon etc. For those cases, memory hotplug lock is a little
too heavy, so introduce a dedicated lock to protect totalram_pages and
zone->managed_pages.
Now we have a simplified locking rules totalram_pages and
zone->managed_pages as:
1) no locking for read accesses because they are unsigned long.
2) no locking for write accesses at boot time in single-threaded context.
3) serialize write accesses at runtime by acquiring the dedicated
managed_page_count_lock.
Also adjust zone->managed_pages when freeing reserved pages into the
buddy system, to keep totalram_pages and zone->managed_pages in
consistence.
[akpm@linux-foundation.org: don't export adjust_managed_page_count to modules (for now)]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michel Lespinasse <walken@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: <sworddragon2@aol.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Historically, kswapd used to congestion_wait() at higher priorities if
it was not making forward progress. This made no sense as the failure
to make progress could be completely independent of IO. It was later
replaced by wait_iff_congested() and removed entirely by commit 258401a6
(mm: don't wait on congested zones in balance_pgdat()) as it was
duplicating logic in shrink_inactive_list().
This is problematic. If kswapd encounters many pages under writeback
and it continues to scan until it reaches the high watermark then it
will quickly skip over the pages under writeback and reclaim clean young
pages or push applications out to swap.
The use of wait_iff_congested() is not suited to kswapd as it will only
stall if the underlying BDI is really congested or a direct reclaimer
was unable to write to the underlying BDI. kswapd bypasses the BDI
congestion as it sets PF_SWAPWRITE but even if this was taken into
account then it would cause direct reclaimers to stall on writeback
which is not desirable.
This patch sets a ZONE_WRITEBACK flag if direct reclaim or kswapd is
encountering too many pages under writeback. If this flag is set and
kswapd encounters a PageReclaim page under writeback then it'll assume
that the LRU lists are being recycled too quickly before IO can complete
and block waiting for some IO to complete.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Tested-by: Zlatko Calusic <zcalusic@bitsync.net>
Cc: dormando <dormando@rydia.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently kswapd queues dirty pages for writeback if scanning at an
elevated priority but the priority kswapd scans at is not related to the
number of unqueued dirty encountered. Since commit "mm: vmscan: Flatten
kswapd priority loop", the priority is related to the size of the LRU
and the zone watermark which is no indication as to whether kswapd
should write pages or not.
This patch tracks if an excessive number of unqueued dirty pages are
being encountered at the end of the LRU. If so, it indicates that dirty
pages are being recycled before flusher threads can clean them and flags
the zone so that kswapd will start writing pages until the zone is
balanced.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Tested-by: Zlatko Calusic <zcalusic@bitsync.net>
Cc: dormando <dormando@rydia.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add pgdat_end_pfn() and pgdat_is_empty() helpers which match the similar
zone_*() functions.
Change node_end_pfn() to be a wrapper of pgdat_end_pfn().
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Hansen <dave@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Factoring out these 2 checks makes it more clear what we are actually
checking for.
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Hansen <dave@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add 2 helpers (zone_end_pfn() and zone_spans_pfn()) to reduce code
duplication.
This also switches to using them in compaction (where an additional
variable needed to be renamed), page_alloc, vmstat, memory_hotplug, and
kmemleak.
Note that in compaction.c I avoid calling zone_end_pfn() repeatedly
because I expect at some point the sycronization issues with start_pfn &
spanned_pages will need fixing, either by actually using the seqlock or
clever memory barrier usage.
Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Hansen <dave@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a preparation patch for moving page->_last_nid into page->flags
that moves page flag layout information to a separate header. This
patch is necessary because otherwise there would be a circular
dependency between mm_types.h and mm.h.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Simon Jeons <simon.jeons@gmail.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Several functions test MIGRATE_ISOLATE and some of those are hotpath but
MIGRATE_ISOLATE is used only if we enable CONFIG_MEMORY_ISOLATION(ie,
CMA, memory-hotplug and memory-failure) which are not common config
option. So let's not add unnecessary overhead and code when we don't
enable CONFIG_MEMORY_ISOLATION.
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 702d1a6e07 ("memory-hotplug: fix kswapd looping forever
problem") added an isolated pageblocks counter (nr_pageblock_isolate in
struct zone) and used it to adjust free pages counter in
zone_watermark_ok_safe() to prevent kswapd looping forever problem.
Then later, commit 2139cbe627 ("cma: fix counting of isolated pages")
fixed accounting of isolated pages in global free pages counter. It
made the previous zone_watermark_ok_safe() fix unnecessary and
potentially harmful (cause now isolated pages may be accounted twice
making free pages counter incorrect).
This patch removes the special isolated pageblocks counter altogether
which fixes zone_watermark_ok_safe() free pages check.
Reported-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Aaditya Kumar <aaditya.kumar.30@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'balancenuma-v11' of git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux-balancenuma
Pull Automatic NUMA Balancing bare-bones from Mel Gorman:
"There are three implementations for NUMA balancing, this tree
(balancenuma), numacore which has been developed in tip/master and
autonuma which is in aa.git.
In almost all respects balancenuma is the dumbest of the three because
its main impact is on the VM side with no attempt to be smart about
scheduling. In the interest of getting the ball rolling, it would be
desirable to see this much merged for 3.8 with the view to building
scheduler smarts on top and adapting the VM where required for 3.9.
The most recent set of comparisons available from different people are
mel: https://lkml.org/lkml/2012/12/9/108
mingo: https://lkml.org/lkml/2012/12/7/331
tglx: https://lkml.org/lkml/2012/12/10/437
srikar: https://lkml.org/lkml/2012/12/10/397
The results are a mixed bag. In my own tests, balancenuma does
reasonably well. It's dumb as rocks and does not regress against
mainline. On the other hand, Ingo's tests shows that balancenuma is
incapable of converging for this workloads driven by perf which is bad
but is potentially explained by the lack of scheduler smarts. Thomas'
results show balancenuma improves on mainline but falls far short of
numacore or autonuma. Srikar's results indicate we all suffer on a
large machine with imbalanced node sizes.
My own testing showed that recent numacore results have improved
dramatically, particularly in the last week but not universally.
We've butted heads heavily on system CPU usage and high levels of
migration even when it shows that overall performance is better.
There are also cases where it regresses. Of interest is that for
specjbb in some configurations it will regress for lower numbers of
warehouses and show gains for higher numbers which is not reported by
the tool by default and sometimes missed in treports. Recently I
reported for numacore that the JVM was crashing with
NullPointerExceptions but currently it's unclear what the source of
this problem is. Initially I thought it was in how numacore batch
handles PTEs but I'm no longer think this is the case. It's possible
numacore is just able to trigger it due to higher rates of migration.
These reports were quite late in the cycle so I/we would like to start
with this tree as it contains much of the code we can agree on and has
not changed significantly over the last 2-3 weeks."
* tag 'balancenuma-v11' of git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux-balancenuma: (50 commits)
mm/rmap, migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable
mm/rmap: Convert the struct anon_vma::mutex to an rwsem
mm: migrate: Account a transhuge page properly when rate limiting
mm: numa: Account for failed allocations and isolations as migration failures
mm: numa: Add THP migration for the NUMA working set scanning fault case build fix
mm: numa: Add THP migration for the NUMA working set scanning fault case.
mm: sched: numa: Delay PTE scanning until a task is scheduled on a new node
mm: sched: numa: Control enabling and disabling of NUMA balancing if !SCHED_DEBUG
mm: sched: numa: Control enabling and disabling of NUMA balancing
mm: sched: Adapt the scanning rate if a NUMA hinting fault does not migrate
mm: numa: Use a two-stage filter to restrict pages being migrated for unlikely task<->node relationships
mm: numa: migrate: Set last_nid on newly allocated page
mm: numa: split_huge_page: Transfer last_nid on tail page
mm: numa: Introduce last_nid to the page frame
sched: numa: Slowly increase the scanning period as NUMA faults are handled
mm: numa: Rate limit setting of pte_numa if node is saturated
mm: numa: Rate limit the amount of memory that is migrated between nodes
mm: numa: Structures for Migrate On Fault per NUMA migration rate limiting
mm: numa: Migrate pages handled during a pmd_numa hinting fault
mm: numa: Migrate on reference policy
...
Currently a zone's present_pages is calcuated as below, which is
inaccurate and may cause trouble to memory hotplug.
spanned_pages - absent_pages - memmap_pages - dma_reserve.
During fixing bugs caused by inaccurate zone->present_pages, we found
zone->present_pages has been abused. The field zone->present_pages may
have different meanings in different contexts:
1) pages existing in a zone.
2) pages managed by the buddy system.
For more discussions about the issue, please refer to:
http://lkml.org/lkml/2012/11/5/866https://patchwork.kernel.org/patch/1346751/
This patchset tries to introduce a new field named "managed_pages" to
struct zone, which counts "pages managed by the buddy system". And revert
zone->present_pages to count "physical pages existing in a zone", which
also keep in consistence with pgdat->node_present_pages.
We will set an initial value for zone->managed_pages in function
free_area_init_core() and will adjust it later if the initial value is
inaccurate.
For DMA/normal zones, the initial value is set to:
(spanned_pages - absent_pages - memmap_pages - dma_reserve)
Later zone->managed_pages will be adjusted to the accurate value when the
bootmem allocator frees all free pages to the buddy system in function
free_all_bootmem_node() and free_all_bootmem().
The bootmem allocator doesn't touch highmem pages, so highmem zones'
managed_pages is set to the accurate value "spanned_pages - absent_pages"
in function free_area_init_core() and won't be updated anymore.
This patch also adds a new field "managed_pages" to /proc/zoneinfo
and sysrq showmem.
[akpm@linux-foundation.org: small comment tweaks]
Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Maciej Rutecki <maciej.rutecki@gmail.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Cc: "Rafael J . Wysocki" <rjw@sisk.pl>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commits 2139cbe627 ("cma: fix counting of isolated pages") and
d95ea5d18e ("cma: fix watermark checking") introduced a reliable
method of free page accounting when memory is being allocated from CMA
regions, so the workaround introduced earlier by commit 49f223a9cd
("mm: trigger page reclaim in alloc_contig_range() to stabilise
watermarks") can be finally removed.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Mel Gorman <mel@csn.ul.ie>
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This defines the per-node data used by Migrate On Fault in order to
rate limit the migration. The rate limiting is applied independently
to each destination node.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
When MEMCG is configured on (even when it's disabled by boot option),
when adding or removing a page to/from its lru list, the zone pointer
used for stats updates is nowadays taken from the struct lruvec. (On
many configurations, calculating zone from page is slower.)
But we have no code to update all the lruvecs (per zone, per memcg) when
a memory node is hotadded. Here's an extract from the oops which
results when running numactl to bind a program to a newly onlined node:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000f60
IP: __mod_zone_page_state+0x9/0x60
Pid: 1219, comm: numactl Not tainted 3.6.0-rc5+ #180 Bochs Bochs
Process numactl (pid: 1219, threadinfo ffff880039abc000, task ffff8800383c4ce0)
Call Trace:
__pagevec_lru_add_fn+0xdf/0x140
pagevec_lru_move_fn+0xb1/0x100
__pagevec_lru_add+0x1c/0x30
lru_add_drain_cpu+0xa3/0x130
lru_add_drain+0x2f/0x40
...
The natural solution might be to use a memcg callback whenever memory is
hotadded; but that solution has not been scoped out, and it happens that
we do have an easy location at which to update lruvec->zone. The lruvec
pointer is discovered either by mem_cgroup_zone_lruvec() or by
mem_cgroup_page_lruvec(), and both of those do know the right zone.
So check and set lruvec->zone in those; and remove the inadequate
attempt to set lruvec->zone from lruvec_init(), which is called before
NODE_DATA(node) has been allocated in such cases.
Ah, there was one exceptionr. For no particularly good reason,
mem_cgroup_force_empty_list() has its own code for deciding lruvec.
Change it to use the standard mem_cgroup_zone_lruvec() and
mem_cgroup_get_lru_size() too. In fact it was already safe against such
an oops (the lru lists in danger could only be empty), but we're better
proofed against future changes this way.
I've marked this for stable (3.6) since we introduced the problem in 3.5
(now closed to stable); but I have no idea if this is the only fix
needed to get memory hotadd working with memcg in 3.6, and received no
answer when I enquired twice before.
Reported-by: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Presently CMA cannot migrate mlocked pages so it ends up failing to allocate
contiguous memory space.
This patch makes mlocked pages be migrated out. Of course, it can affect
realtime processes but in CMA usecase, contiguous memory allocation failing
is far worse than access latency to an mlocked page being variable while
CMA is running. If someone wants to make the system realtime, he shouldn't
enable CMA because stalls can still happen at random times.
[akpm@linux-foundation.org: tweak comment text, per Mel]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
RECLAIM_DISTANCE represents the distance between nodes at which it is
deemed too costly to allocate from; it's preferred to try to reclaim from
a local zone before falling back to allocating on a remote node with such
a distance.
To do this, zone_reclaim_mode is set if the distance between any two
nodes on the system is greather than this distance. This, however, ends
up causing the page allocator to reclaim from every zone regardless of
its affinity.
What we really want is to reclaim only from zones that are closer than
RECLAIM_DISTANCE. This patch adds a nodemask to each node that
represents the set of nodes that are within this distance. During the
zone iteration, if the bit for a zone's node is set for the local node,
then reclaim is attempted; otherwise, the zone is skipped.
[akpm@linux-foundation.org: fix CONFIG_NUMA=n build]
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Minchan Kim <minchan@kernel.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Compaction caches if a pageblock was scanned and no pages were isolated so
that the pageblocks can be skipped in the future to reduce scanning. This
information is not cleared by the page allocator based on activity due to
the impact it would have to the page allocator fast paths. Hence there is
a requirement that something clear the cache or pageblocks will be skipped
forever. Currently the cache is cleared if there were a number of recent
allocation failures and it has not been cleared within the last 5 seconds.
Time-based decisions like this are terrible as they have no relationship
to VM activity and is basically a big hammer.
Unfortunately, accurate heuristics would add cost to some hot paths so
this patch implements a rough heuristic. There are two cases where the
cache is cleared.
1. If a !kswapd process completes a compaction cycle (migrate and free
scanner meet), the zone is marked compact_blockskip_flush. When kswapd
goes to sleep, it will clear the cache. This is expected to be the
common case where the cache is cleared. It does not really matter if
kswapd happens to be asleep or going to sleep when the flag is set as
it will be woken on the next allocation request.
2. If there have been multiple failures recently and compaction just
finished being deferred then a process will clear the cache and start a
full scan. This situation happens if there are multiple high-order
allocation requests under heavy memory pressure.
The clearing of the PG_migrate_skip bits and other scans is inherently
racy but the race is harmless. For allocations that can fail such as THP,
they will simply fail. For requests that cannot fail, they will retry the
allocation. Tests indicated that scanning rates were roughly similar to
when the time-based heuristic was used and the allocation success rates
were similar.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Richard Davies <richard@arachsys.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Cc: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is almost entirely based on Rik's previous patches and discussions
with him about how this might be implemented.
Order > 0 compaction stops when enough free pages of the correct page
order have been coalesced. When doing subsequent higher order
allocations, it is possible for compaction to be invoked many times.
However, the compaction code always starts out looking for things to
compact at the start of the zone, and for free pages to compact things to
at the end of the zone.
This can cause quadratic behaviour, with isolate_freepages starting at the
end of the zone each time, even though previous invocations of the
compaction code already filled up all free memory on that end of the zone.
This can cause isolate_freepages to take enormous amounts of CPU with
certain workloads on larger memory systems.
This patch caches where the migration and free scanner should start from
on subsequent compaction invocations using the pageblock-skip information.
When compaction starts it begins from the cached restart points and will
update the cached restart points until a page is isolated or a pageblock
is skipped that would have been scanned by synchronous compaction.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Richard Davies <richard@arachsys.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When compaction was implemented it was known that scanning could
potentially be excessive. The ideal was that a counter be maintained for
each pageblock but maintaining this information would incur a severe
penalty due to a shared writable cache line. It has reached the point
where the scanning costs are a serious problem, particularly on
long-lived systems where a large process starts and allocates a large
number of THPs at the same time.
Instead of using a shared counter, this patch adds another bit to the
pageblock flags called PG_migrate_skip. If a pageblock is scanned by
either migrate or free scanner and 0 pages were isolated, the pageblock is
marked to be skipped in the future. When scanning, this bit is checked
before any scanning takes place and the block skipped if set.
The main difficulty with a patch like this is "when to ignore the cached
information?" If it's ignored too often, the scanning rates will still be
excessive. If the information is too stale then allocations will fail
that might have otherwise succeeded. In this patch
o CMA always ignores the information
o If the migrate and free scanner meet then the cached information will
be discarded if it's at least 5 seconds since the last time the cache
was discarded
o If there are a large number of allocation failures, discard the cache.
The time-based heuristic is very clumsy but there are few choices for a
better event. Depending solely on multiple allocation failures still
allows excessive scanning when THP allocations are failing in quick
succession due to memory pressure. Waiting until memory pressure is
relieved would cause compaction to continually fail instead of using
reclaim/compaction to try allocate the page. The time-based mechanism is
clumsy but a better option is not obvious.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Richard Davies <richard@arachsys.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 7db8889ab0 ("mm: have order > 0 compaction start
off where it left") and commit de74f1cc ("mm: have order > 0 compaction
start near a pageblock with free pages"). These patches were a good
idea and tests confirmed that they massively reduced the amount of
scanning but the implementation is complex and tricky to understand. A
later patch will cache what pageblocks should be skipped and
reimplements the concept of compact_cached_free_pfn on top for both
migration and free scanners.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Richard Davies <richard@arachsys.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add NR_FREE_CMA_PAGES counter to be later used for checking watermark in
__zone_watermark_ok(). For simplicity and to avoid #ifdef hell make this
counter always available (not only when CONFIG_CMA=y).
[akpm@linux-foundation.org: use conventional migratetype naming]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If swap is backed by network storage such as NBD, there is a risk that a
large number of reclaimers can hang the system by consuming all
PF_MEMALLOC reserves. To avoid these hangs, the administrator must tune
min_free_kbytes in advance which is a bit fragile.
This patch throttles direct reclaimers if half the PF_MEMALLOC reserves
are in use. If the system is routinely getting throttled the system
administrator can increase min_free_kbytes so degradation is smoother but
the system will keep running.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When hotplug offlining happens on zone A, it starts to mark freed page as
MIGRATE_ISOLATE type in buddy for preventing further allocation.
(MIGRATE_ISOLATE is very irony type because it's apparently on buddy but
we can't allocate them).
When the memory shortage happens during hotplug offlining, current task
starts to reclaim, then wake up kswapd. Kswapd checks watermark, then go
sleep because current zone_watermark_ok_safe doesn't consider
MIGRATE_ISOLATE freed page count. Current task continue to reclaim in
direct reclaim path without kswapd's helping. The problem is that
zone->all_unreclaimable is set by only kswapd so that current task would
be looping forever like below.
__alloc_pages_slowpath
restart:
wake_all_kswapd
rebalance:
__alloc_pages_direct_reclaim
do_try_to_free_pages
if global_reclaim && !all_unreclaimable
return 1; /* It means we did did_some_progress */
skip __alloc_pages_may_oom
should_alloc_retry
goto rebalance;
If we apply KOSAKI's patch[1] which doesn't depends on kswapd about
setting zone->all_unreclaimable, we can solve this problem by killing some
task in direct reclaim path. But it doesn't wake up kswapd, still. It
could be a problem still if other subsystem needs GFP_ATOMIC request. So
kswapd should consider MIGRATE_ISOLATE when it calculate free pages BEFORE
going sleep.
This patch counts the number of MIGRATE_ISOLATE page block and
zone_watermark_ok_safe will consider it if the system has such blocks
(fortunately, it's very rare so no problem in POV overhead and kswapd is
never hotpath).
Copy/modify from Mel's quote
"
Ideal solution would be "allocating" the pageblock.
It would keep the free space accounting as it is but historically,
memory hotplug didn't allocate pages because it would be difficult to
detect if a pageblock was isolated or if part of some balloon.
Allocating just full pageblocks would work around this, However,
it would play very badly with CMA.
"
[1] http://lkml.org/lkml/2012/6/14/74
[akpm@linux-foundation.org: simplify nr_zone_isolate_freepages(), rework zone_watermark_ok_safe() comment, simplify set_pageblock_isolate() and restore_pageblock_isolate()]
[akpm@linux-foundation.org: fix CONFIG_MEMORY_ISOLATION=n build]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Suggested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: Aaditya Kumar <aaditya.kumar.30@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When hotadd_new_pgdat() is called to create new pgdat for a new node, a
fallback zonelist should be created for the new node. There's code to try
to achieve that in hotadd_new_pgdat() as below:
/*
* The node we allocated has no zone fallback lists. For avoiding
* to access not-initialized zonelist, build here.
*/
mutex_lock(&zonelists_mutex);
build_all_zonelists(pgdat, NULL);
mutex_unlock(&zonelists_mutex);
But it doesn't work as expected. When hotadd_new_pgdat() is called, the
new node is still in offline state because node_set_online(nid) hasn't
been called yet. And build_all_zonelists() only builds zonelists for
online nodes as:
for_each_online_node(nid) {
pg_data_t *pgdat = NODE_DATA(nid);
build_zonelists(pgdat);
build_zonelist_cache(pgdat);
}
Though we hope to create zonelist for the new pgdat, but it doesn't. So
add a new parameter "pgdat" the build_all_zonelists() to build pgdat for
the new pgdat too.
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Keping Chen <chenkeping@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
0ee332c145 ("memblock: Kill early_node_map[]") wanted to replace
CONFIG_ARCH_POPULATES_NODE_MAP with CONFIG_HAVE_MEMBLOCK_NODE_MAP but
ended up replacing one occurence with a reference to the non-existent
symbol CONFIG_HAVE_MEMBLOCK_NODE.
The resulting omission of code would probably have been causing problems
to 32-bit machines with memory hotplug.
Signed-off-by: Rabin Vincent <rabin@rab.in>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Order > 0 compaction stops when enough free pages of the correct page
order have been coalesced. When doing subsequent higher order
allocations, it is possible for compaction to be invoked many times.
However, the compaction code always starts out looking for things to
compact at the start of the zone, and for free pages to compact things to
at the end of the zone.
This can cause quadratic behaviour, with isolate_freepages starting at the
end of the zone each time, even though previous invocations of the
compaction code already filled up all free memory on that end of the zone.
This can cause isolate_freepages to take enormous amounts of CPU with
certain workloads on larger memory systems.
The obvious solution is to have isolate_freepages remember where it left
off last time, and continue at that point the next time it gets invoked
for an order > 0 compaction. This could cause compaction to fail if
cc->free_pfn and cc->migrate_pfn are close together initially, in that
case we restart from the end of the zone and try once more.
Forced full (order == -1) compactions are left alone.
[akpm@linux-foundation.org: checkpatch fixes]
[akpm@linux-foundation.org: s/laste/last/, use 80 cols]
Signed-off-by: Rik van Riel <riel@redhat.com>
Reported-by: Jim Schutt <jaschut@sandia.gov>
Tested-by: Jim Schutt <jaschut@sandia.gov>
Cc: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull trivial tree from Jiri Kosina:
"Trivial updates all over the place as usual."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (29 commits)
Fix typo in include/linux/clk.h .
pci: hotplug: Fix typo in pci
iommu: Fix typo in iommu
video: Fix typo in drivers/video
Documentation: Add newline at end-of-file to files lacking one
arm,unicore32: Remove obsolete "select MISC_DEVICES"
module.c: spelling s/postition/position/g
cpufreq: Fix typo in cpufreq driver
trivial: typo in comment in mksysmap
mach-omap2: Fix typo in debug message and comment
scsi: aha152x: Fix sparse warning and make printing pointer address more portable.
Change email address for Steve Glendinning
Btrfs: fix typo in convert_extent_bit
via: Remove bogus if check
netprio_cgroup.c: fix comment typo
backlight: fix memory leak on obscure error path
Documentation: asus-laptop.txt references an obsolete Kconfig item
Documentation: ManagementStyle: fixed typo
mm/vmscan: cleanup comment error in balance_pgdat
mm: cleanup on the comments of zone_reclaim_stat
...
Conflicts:
include/linux/mmzone.h
Synced with Linus' tree so that trivial patch can be applied
on top of up-to-date code properly.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
This is the first stage of struct mem_cgroup_zone removal. Further
patches replace struct mem_cgroup_zone with a pointer to struct lruvec.
If CONFIG_CGROUP_MEM_RES_CTLR=n lruvec_zone() is just container_of().
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
With mem_cgroup_disabled() now explicit, it becomes clear that the
zone_reclaim_stat structure actually belongs in lruvec, per-zone when
memcg is disabled but per-memcg per-zone when it's enabled.
We can delete mem_cgroup_get_reclaim_stat(), and change
update_page_reclaim_stat() to update just the one set of stats, the one
which get_scan_count() will actually use.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After patch "mm: forbid lumpy-reclaim in shrink_active_list()" we can
completely remove anon/file and active/inactive lru type filters from
__isolate_lru_page(), because isolation for 0-order reclaim always
isolates pages from right lru list. And pages-isolation for lumpy
shrink_inactive_list() or memory-compaction anyway allowed to isolate
pages from all evictable lru lists.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull CMA and ARM DMA-mapping updates from Marek Szyprowski:
"These patches contain two major updates for DMA mapping subsystem
(mainly for ARM architecture). First one is Contiguous Memory
Allocator (CMA) which makes it possible for device drivers to allocate
big contiguous chunks of memory after the system has booted.
The main difference from the similar frameworks is the fact that CMA
allows to transparently reuse the memory region reserved for the big
chunk allocation as a system memory, so no memory is wasted when no
big chunk is allocated. Once the alloc request is issued, the
framework migrates system pages to create space for the required big
chunk of physically contiguous memory.
For more information one can refer to nice LWN articles:
- 'A reworked contiguous memory allocator':
http://lwn.net/Articles/447405/
- 'CMA and ARM':
http://lwn.net/Articles/450286/
- 'A deep dive into CMA':
http://lwn.net/Articles/486301/
- and the following thread with the patches and links to all previous
versions:
https://lkml.org/lkml/2012/4/3/204
The main client for this new framework is ARM DMA-mapping subsystem.
The second part provides a complete redesign in ARM DMA-mapping
subsystem. The core implementation has been changed to use common
struct dma_map_ops based infrastructure with the recent updates for
new dma attributes merged in v3.4-rc2. This allows to use more than
one implementation of dma-mapping calls and change/select them on the
struct device basis. The first client of this new infractructure is
dmabounce implementation which has been completely cut out of the
core, common code.
The last patch of this redesign update introduces a new, experimental
implementation of dma-mapping calls on top of generic IOMMU framework.
This lets ARM sub-platform to transparently use IOMMU for DMA-mapping
calls if one provides required IOMMU hardware.
For more information please refer to the following thread:
http://www.spinics.net/lists/arm-kernel/msg175729.html
The last patch merges changes from both updates and provides a
resolution for the conflicts which cannot be avoided when patches have
been applied on the same files (mainly arch/arm/mm/dma-mapping.c)."
Acked by Andrew Morton <akpm@linux-foundation.org>:
"Yup, this one please. It's had much work, plenty of review and I
think even Russell is happy with it."
* 'for-linus' of git://git.linaro.org/people/mszyprowski/linux-dma-mapping: (28 commits)
ARM: dma-mapping: use PMD size for section unmap
cma: fix migration mode
ARM: integrate CMA with DMA-mapping subsystem
X86: integrate CMA with DMA-mapping subsystem
drivers: add Contiguous Memory Allocator
mm: trigger page reclaim in alloc_contig_range() to stabilise watermarks
mm: extract reclaim code from __alloc_pages_direct_reclaim()
mm: Serialize access to min_free_kbytes
mm: page_isolation: MIGRATE_CMA isolation functions added
mm: mmzone: MIGRATE_CMA migration type added
mm: page_alloc: change fallbacks array handling
mm: page_alloc: introduce alloc_contig_range()
mm: compaction: export some of the functions
mm: compaction: introduce isolate_freepages_range()
mm: compaction: introduce map_pages()
mm: compaction: introduce isolate_migratepages_range()
mm: page_alloc: remove trailing whitespace
ARM: dma-mapping: add support for IOMMU mapper
ARM: dma-mapping: use alloc, mmap, free from dma_ops
ARM: dma-mapping: remove redundant code and do the cleanup
...
Conflicts:
arch/x86/include/asm/dma-mapping.h
alloc_contig_range() performs memory allocation so it also should keep
track on keeping the correct level of memory watermarks. This commit adds
a call to *_slowpath style reclaim to grab enough pages to make sure that
the final collection of contiguous pages from freelists will not starve
the system.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Michal Nazarewicz <mina86@mina86.com>
Tested-by: Rob Clark <rob.clark@linaro.org>
Tested-by: Ohad Ben-Cohen <ohad@wizery.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Tested-by: Barry Song <Baohua.Song@csr.com>
The MIGRATE_CMA migration type has two main characteristics:
(i) only movable pages can be allocated from MIGRATE_CMA
pageblocks and (ii) page allocator will never change migration
type of MIGRATE_CMA pageblocks.
This guarantees (to some degree) that page in a MIGRATE_CMA page
block can always be migrated somewhere else (unless there's no
memory left in the system).
It is designed to be used for allocating big chunks (eg. 10MiB)
of physically contiguous memory. Once driver requests
contiguous memory, pages from MIGRATE_CMA pageblocks may be
migrated away to create a contiguous block.
To minimise number of migrations, MIGRATE_CMA migration type
is the last type tried when page allocator falls back to other
migration types when requested.
Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: Rob Clark <rob.clark@linaro.org>
Tested-by: Ohad Ben-Cohen <ohad@wizery.com>
Tested-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Tested-by: Robert Nelson <robertcnelson@gmail.com>
Tested-by: Barry Song <Baohua.Song@csr.com>
Currently a failed order-9 (transparent hugepage) compaction can lead to
memory compaction being temporarily disabled for a memory zone. Even if
we only need compaction for an order 2 allocation, eg. for jumbo frames
networking.
The fix is relatively straightforward: keep track of the highest order at
which compaction is succeeding, and only defer compaction for orders at
which compaction is failing.
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Mostly we use "enum lru_list lru": change those few "l"s to "lru"s.
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 39deaf85 ("mm: compaction: make isolate_lru_page() filter-aware")
noted that compaction does not migrate dirty or writeback pages and that
is was meaningless to pick the page and re-add it to the LRU list. This
had to be partially reverted because some dirty pages can be migrated by
compaction without blocking.
This patch updates "mm: compaction: make isolate_lru_page" by skipping
over pages that migration has no possibility of migrating to minimise LRU
disruption.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel<riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andy Isaacson <adi@hexapodia.org>
Cc: Nai Xia <nai.xia@gmail.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>