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mm: vmscan: move direct reclaim wait_iff_congested into shrink_list 

shrink_inactive_list makes decisions on whether to stall based on the
number of dirty pages encountered.  The wait_iff_congested() call in
shrink_page_list does no such thing and it's arbitrary.

This patch moves the decision on whether to set ZONE_CONGESTED and the
wait_iff_congested call into shrink_page_list.  This keeps all the
decisions on whether to stall or not in the one place.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Zlatko Calusic <zcalusic@bitsync.net>
Cc: dormando <dormando@rydia.net>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2013-07-03 15:02:02 -07:00 committed by Linus Torvalds
parent f7ab8db791
commit 8e95028280
1 changed files with 33 additions and 29 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

62
mm/vmscan.c
View File

@ -695,7 +695,9 @@ static unsigned long shrink_page_list(struct list_head *page_list,
struct zone *zone,
struct scan_control *sc,
enum ttu_flags ttu_flags,
unsigned long *ret_nr_dirty,
unsigned long *ret_nr_unqueued_dirty,
unsigned long *ret_nr_congested,
unsigned long *ret_nr_writeback,
unsigned long *ret_nr_immediate,
bool force_reclaim)
@ -1017,20 +1019,13 @@ keep:
VM_BUG_ON(PageLRU(page) || PageUnevictable(page));
}
/*
* Tag a zone as congested if all the dirty pages encountered were
* backed by a congested BDI. In this case, reclaimers should just
* back off and wait for congestion to clear because further reclaim
* will encounter the same problem
*/
if (nr_dirty && nr_dirty == nr_congested && global_reclaim(sc))
zone_set_flag(zone, ZONE_CONGESTED);
free_hot_cold_page_list(&free_pages, 1);
list_splice(&ret_pages, page_list);
count_vm_events(PGACTIVATE, pgactivate);
mem_cgroup_uncharge_end();
*ret_nr_dirty += nr_dirty;
*ret_nr_congested += nr_congested;
*ret_nr_unqueued_dirty += nr_unqueued_dirty;
*ret_nr_writeback += nr_writeback;
*ret_nr_immediate += nr_immediate;
@ -1045,7 +1040,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
.priority = DEF_PRIORITY,
.may_unmap = 1,
};
unsigned long ret, dummy1, dummy2, dummy3;
unsigned long ret, dummy1, dummy2, dummy3, dummy4, dummy5;
struct page *page, *next;
LIST_HEAD(clean_pages);
@ -1057,8 +1052,8 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
}
ret = shrink_page_list(&clean_pages, zone, &sc,
TTU_UNMAP|TTU_IGNORE_ACCESS,
&dummy1, &dummy2, &dummy3, true);
TTU_UNMAP|TTU_IGNORE_ACCESS,
&dummy1, &dummy2, &dummy3, &dummy4, &dummy5, true);
list_splice(&clean_pages, page_list);
__mod_zone_page_state(zone, NR_ISOLATED_FILE, -ret);
return ret;
@ -1352,6 +1347,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
unsigned long nr_scanned;
unsigned long nr_reclaimed = 0;
unsigned long nr_taken;
unsigned long nr_dirty = 0;
unsigned long nr_congested = 0;
unsigned long nr_unqueued_dirty = 0;
unsigned long nr_writeback = 0;
unsigned long nr_immediate = 0;
@ -1396,8 +1393,9 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
return 0;
nr_reclaimed = shrink_page_list(&page_list, zone, sc, TTU_UNMAP,
&nr_unqueued_dirty, &nr_writeback, &nr_immediate,
false);
&nr_dirty, &nr_unqueued_dirty, &nr_congested,
&nr_writeback, &nr_immediate,
false);
spin_lock_irq(&zone->lru_lock);
@ -1431,7 +1429,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
* same way balance_dirty_pages() manages.
*
* This scales the number of dirty pages that must be under writeback
* before throttling depending on priority. It is a simple backoff
* before a zone gets flagged ZONE_WRITEBACK. It is a simple backoff
* function that has the most effect in the range DEF_PRIORITY to
* DEF_PRIORITY-2 which is the priority reclaim is considered to be
* in trouble and reclaim is considered to be in trouble.
@ -1442,18 +1440,27 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
* ...
* DEF_PRIORITY-6 For SWAP_CLUSTER_MAX isolated pages, throttle if any
* isolated page is PageWriteback
*
* Once a zone is flagged ZONE_WRITEBACK, kswapd will count the number
* of pages under pages flagged for immediate reclaim and stall if any
* are encountered in the nr_immediate check below.
*/
if (nr_writeback && nr_writeback >=
(nr_taken >> (DEF_PRIORITY - sc->priority))) {
(nr_taken >> (DEF_PRIORITY - sc->priority)))
zone_set_flag(zone, ZONE_WRITEBACK);
wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
}
/*
* memcg will stall in page writeback so only consider forcibly
* stalling for global reclaim
*/
if (global_reclaim(sc)) {
/*
* Tag a zone as congested if all the dirty pages scanned were
* backed by a congested BDI and wait_iff_congested will stall.
*/
if (nr_dirty && nr_dirty == nr_congested)
zone_set_flag(zone, ZONE_CONGESTED);
/*
* If dirty pages are scanned that are not queued for IO, it
* implies that flushers are not keeping up. In this case, flag
@ -1474,6 +1481,14 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
congestion_wait(BLK_RW_ASYNC, HZ/10);
}
/*
* Stall direct reclaim for IO completions if underlying BDIs or zone
* is congested. Allow kswapd to continue until it starts encountering
* unqueued dirty pages or cycling through the LRU too quickly.
*/
if (!sc->hibernation_mode && !current_is_kswapd())
wait_iff_congested(zone, BLK_RW_ASYNC, HZ/10);
trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
zone_idx(zone),
nr_scanned, nr_reclaimed,
@ -2374,17 +2389,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
WB_REASON_TRY_TO_FREE_PAGES);
sc->may_writepage = 1;
}
/* Take a nap, wait for some writeback to complete */
if (!sc->hibernation_mode && sc->nr_scanned &&
sc->priority < DEF_PRIORITY - 2) {
struct zone *preferred_zone;
first_zones_zonelist(zonelist, gfp_zone(sc->gfp_mask),
&cpuset_current_mems_allowed,
&preferred_zone);
wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/10);
}
} while (--sc->priority >= 0);
out: