linux-stable/mm
Ingo Molnar 1233d58821 mm: Optimize the TLB flush of sys_mprotect() and change_protection() users
Reuse the NUMA code's 'modified page protections' count that
change_protection() computes and skip the TLB flush if there's
no changes to a range that sys_mprotect() modifies.

Given that mprotect() already optimizes the same-flags case
I expected this optimization to dominantly trigger on
CONFIG_NUMA_BALANCING=y kernels - but even with that feature
disabled it triggers rather often.

There's two reasons for that:

1)

While sys_mprotect() already optimizes the same-flag case:

        if (newflags == oldflags) {
                *pprev = vma;
                return 0;
        }

and this test works in many cases, but it is too sharp in some
others, where it differentiates between protection values that the
underlying PTE format makes no distinction about, such as
PROT_EXEC == PROT_READ on x86.

2)

Even where the pte format over vma flag changes necessiates a
modification of the pagetables, there might be no pagetables
yet to modify: they might not be instantiated yet.

During a regular desktop bootup this optimization hits a couple
of hundred times. During a Java test I measured thousands of
hits.

So this optimization improves sys_mprotect() in general, not just
CONFIG_NUMA_BALANCING=y kernels.

[ We could further increase the efficiency of this optimization if
  change_pte_range() and change_huge_pmd() was a bit smarter about
  recognizing exact-same-value protection masks - when the hardware
  can do that safely. This would probably further speed up mprotect(). ]

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2012-12-11 14:28:34 +00:00
..
backing-dev.c backing-dev: use kstrto* in preference to simple_strtoul 2012-08-25 16:58:14 +08:00
bootmem.c revert "mm: fix-up zone present pages" 2012-11-16 14:33:04 -08:00
bounce.c bounce: allow use of bounce pool via config option 2012-07-18 16:40:35 -04:00
cleancache.c ->encode_fh() API change 2012-05-29 23:28:33 -04:00
compaction.c mm: compaction: correct the nr_strict va isolated check for CMA 2012-10-19 14:07:47 -07:00
debug-pagealloc.c mm, x86: Remove debug_pagealloc_enabled 2011-12-06 09:24:07 +01:00
dmapool.c mm: fix implicit stat.h usage in dmapool.c 2011-10-31 09:20:12 -04:00
fadvise.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
failslab.c switch debugfs to umode_t 2012-01-03 22:54:56 -05:00
filemap.c readahead: fault retry breaks mmap file read random detection 2012-10-09 16:22:47 +09:00
filemap_xip.c mm: move all mmu notifier invocations to be done outside the PT lock 2012-10-09 16:22:58 +09:00
fremap.c remap_file_pages: correctly handle the case of a NULL vm_ops pointer 2012-10-19 13:37:57 -07:00
frontswap.c frontswap: support exclusive gets if tmem backend is capable 2012-09-21 10:38:12 -04:00
highmem.c mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address 2012-11-16 14:33:04 -08:00
huge_memory.c mm: Check if PTE is already allocated during page fault 2012-12-11 14:28:34 +00:00
hugetlb.c mm: Count the number of pages affected in change_protection() 2012-12-11 14:28:34 +00:00
hugetlb_cgroup.c hugetlb/cgroup: remove exclude and wakeup rmdir calls from migrate 2012-07-31 18:42:41 -07:00
hwpoison-inject.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
init-mm.c atomic: use <linux/atomic.h> 2011-07-26 16:49:47 -07:00
internal.h mm, thp: fix mlock statistics 2012-10-09 16:23:03 +09:00
interval_tree.c mm: add CONFIG_DEBUG_VM_RB build option 2012-10-09 16:22:42 +09:00
Kconfig mm: enable CONFIG_COMPACTION by default 2012-10-09 16:22:53 +09:00
Kconfig.debug mm: more intensive memory corruption debugging 2012-01-10 16:30:42 -08:00
kmemcheck.c
kmemleak-test.c
kmemleak.c kmemleak: use rbtree instead of prio tree 2012-10-09 16:22:39 +09:00
ksm.c mm: wrap calls to set_pte_at_notify with invalidate_range_start and invalidate_range_end 2012-10-09 16:22:58 +09:00
maccess.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
madvise.c mm: prepare VM_DONTDUMP for using in drivers 2012-10-09 16:22:18 +09:00
Makefile mm: replace vma prio_tree with an interval tree 2012-10-09 16:22:39 +09:00
memblock.c x86, mm: Trim memory in memblock to be page aligned 2012-10-24 11:52:21 -07:00
memcontrol.c memcg: fix hotplugged memory zone oops 2012-11-16 14:33:04 -08:00
memory-failure.c mm anon rmap: replace same_anon_vma linked list with an interval tree. 2012-10-09 16:22:41 +09:00
memory.c mm: Check if PTE is already allocated during page fault 2012-12-11 14:28:34 +00:00
memory_hotplug.c revert "mm: fix-up zone present pages" 2012-11-16 14:33:04 -08:00
mempolicy.c mm, mempolicy: fix printing stack contents in numa_maps 2012-10-16 18:00:50 -07:00
mempool.c mempool: add @gfp_mask to mempool_create_node() 2012-06-25 11:53:47 +02:00
migrate.c mm: memcg: fix compaction/migration failing due to memcg limits 2012-07-31 18:42:48 -07:00
mincore.c mm: thp: fix pmd_bad() triggering in code paths holding mmap_sem read mode 2012-03-21 17:54:54 -07:00
mlock.c mm, thp: fix mlock statistics 2012-10-09 16:23:03 +09:00
mm_init.c mm: Map most files to use export.h instead of module.h 2011-10-31 09:20:12 -04:00
mmap.c mm: add anon_vma_lock to validate_mm() 2012-11-16 14:33:03 -08:00
mmu_context.c mm, counters: remove task argument to sync_mm_rss() and __sync_task_rss_stat() 2012-03-21 17:54:59 -07:00
mmu_notifier.c mm/mmu_notifier: allocate mmu_notifier in advance 2012-10-25 14:37:53 -07:00
mmzone.c memcg: fix hotplugged memory zone oops 2012-11-16 14:33:04 -08:00
mprotect.c mm: Optimize the TLB flush of sys_mprotect() and change_protection() users 2012-12-11 14:28:34 +00:00
mremap.c mm: move all mmu notifier invocations to be done outside the PT lock 2012-10-09 16:22:58 +09:00
msync.c
nobootmem.c revert "mm: fix-up zone present pages" 2012-11-16 14:33:04 -08:00
nommu.c mm: replace vma prio_tree with an interval tree 2012-10-09 16:22:39 +09:00
oom_kill.c oom: remove deprecated oom_adj 2012-10-09 16:22:24 +09:00
page-writeback.c CPU hotplug, writeback: Don't call writeback_set_ratelimit() too often during hotplug 2012-09-28 20:27:49 +08:00
page_alloc.c revert "mm: fix-up zone present pages" 2012-11-16 14:33:04 -08:00
page_cgroup.c memcg: rename config variables 2012-07-31 18:42:43 -07:00
page_io.c mm: add support for direct_IO to highmem pages 2012-07-31 18:42:47 -07:00
page_isolation.c mm/page_alloc: refactor out __alloc_contig_migrate_alloc() 2012-10-09 16:22:52 +09:00
pagewalk.c mm: fix kernel-doc warnings 2012-06-20 14:39:36 -07:00
percpu-km.c
percpu-vm.c mm: fix kernel-doc warnings 2012-06-20 14:39:36 -07:00
percpu.c sections: fix section conflicts in mm/percpu.c 2012-10-06 03:04:44 +09:00
pgtable-generic.c mm: Only flush the TLB when clearing an accessible pte 2012-12-11 14:28:34 +00:00
process_vm_access.c aio/vfs: cleanup of rw_copy_check_uvector() and compat_rw_copy_check_uvector() 2012-05-31 17:49:32 -07:00
quicklist.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
readahead.c switch simple cases of fget_light to fdget 2012-09-26 22:20:08 -04:00
rmap.c mm: fix XFS oops due to dirty pages without buffers on s390 2012-10-25 14:37:52 -07:00
shmem.c tmpfs: change final i_blocks BUG to WARNING 2012-11-16 14:33:04 -08:00
slab.c Merge branch 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux 2012-10-07 07:53:13 +09:00
slab.h Revert "mm/sl[aou]b: Move sysfs_slab_add to common" 2012-09-05 12:07:44 +03:00
slab_common.c mm, slab: release slab_mutex earlier in kmem_cache_destroy() 2012-10-10 09:25:08 +03:00
slob.c Merge branch 'testing/driver-warnings' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc into fixes 2012-10-19 15:40:18 -07:00
slub.c Merge branch 'slab/common-for-cgroups' into slab/for-linus 2012-10-03 09:56:37 +03:00
sparse-vmemmap.c mm: delete various needless include <linux/module.h> 2011-10-31 09:20:11 -04:00
sparse.c mm/sparse: remove index_init_lock 2012-07-31 18:42:49 -07:00
swap.c mm: remove vma arg from page_evictable 2012-10-09 16:22:55 +09:00
swap_state.c mm: add support for a filesystem to activate swap files and use direct_IO for writing swap pages 2012-07-31 18:42:47 -07:00
swapfile.c swapfile: fix name leak in swapoff 2012-11-16 14:33:04 -08:00
truncate.c mm: use clear_page_mlock() in page_remove_rmap() 2012-10-09 16:22:56 +09:00
util.c mm: Use __do_krealloc to do the krealloc job 2012-09-04 10:22:58 +03:00
vmalloc.c mm: use %pK for /proc/vmallocinfo 2012-10-09 16:23:03 +09:00
vmscan.c mm: revert "mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures" 2012-11-16 14:33:04 -08:00
vmstat.c mm: remove unevictable_pgs_mlockfreed 2012-10-09 16:22:59 +09:00