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author | David Rientjes <rientjes@google.com> | 2007-10-16 23:26:01 -0700 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-10-17 08:42:46 -0700 |
commit | d773ed6b856a96bd6d18b6e04455e3ced0876da4 (patch) | |
tree | f0235be6843ec323aeedcdadbee34a777b6c2690 /mm | |
parent | ae74138da609c576b221c765efa8b81b2365f465 (diff) | |
download | linux-stable-d773ed6b856a96bd6d18b6e04455e3ced0876da4.tar.gz linux-stable-d773ed6b856a96bd6d18b6e04455e3ced0876da4.tar.bz2 linux-stable-d773ed6b856a96bd6d18b6e04455e3ced0876da4.zip |
mm: test and set zone reclaim lock before starting reclaim
Introduces new zone flag interface for testing and setting flags:
int zone_test_and_set_flag(struct zone *zone, zone_flags_t flag)
Instead of setting and clearing ZONE_RECLAIM_LOCKED each time shrink_zone() is
called, this flag is test and set before starting zone reclaim. Zone reclaim
starts in __alloc_pages() when a zone's watermark fails and the system is in
zone_reclaim_mode. If it's already in reclaim, there's no need to start again
so it is simply considered full for that allocation attempt.
There is a change of behavior with regard to concurrent zone shrinking. It is
now possible for try_to_free_pages() or kswapd to already be shrinking a
particular zone when __alloc_pages() starts zone reclaim. In this case, it is
possible for two concurrent threads to invoke shrink_zone() for a single zone.
This change forbids a zone to be in zone reclaim twice, which was always the
behavior, but allows for concurrent try_to_free_pages() or kswapd shrinking
when starting zone reclaim.
Cc: Andrea Arcangeli <andrea@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/vmscan.c | 23 |
1 files changed, 13 insertions, 10 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c index d8893dc2d4eb..e1471385d001 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1108,8 +1108,6 @@ static unsigned long shrink_zone(int priority, struct zone *zone, unsigned long nr_to_scan; unsigned long nr_reclaimed = 0; - zone_set_flag(zone, ZONE_RECLAIM_LOCKED); - /* * Add one to `nr_to_scan' just to make sure that the kernel will * slowly sift through the active list. @@ -1148,8 +1146,6 @@ static unsigned long shrink_zone(int priority, struct zone *zone, } throttle_vm_writeout(sc->gfp_mask); - - zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); return nr_reclaimed; } @@ -1900,6 +1896,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) { int node_id; + int ret; /* * Zone reclaim reclaims unmapped file backed pages and @@ -1917,13 +1914,13 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) <= zone->min_slab_pages) return 0; + if (zone_is_all_unreclaimable(zone)) + return 0; + /* - * Avoid concurrent zone reclaims, do not reclaim in a zone that does - * not have reclaimable pages and if we should not delay the allocation - * then do not scan. + * Do not scan if the allocation should not be delayed. */ - if (!(gfp_mask & __GFP_WAIT) || zone_is_all_unreclaimable(zone) || - zone_is_reclaim_locked(zone) || (current->flags & PF_MEMALLOC)) + if (!(gfp_mask & __GFP_WAIT) || (current->flags & PF_MEMALLOC)) return 0; /* @@ -1935,6 +1932,12 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) node_id = zone_to_nid(zone); if (node_state(node_id, N_CPU) && node_id != numa_node_id()) return 0; - return __zone_reclaim(zone, gfp_mask, order); + + if (zone_test_and_set_flag(zone, ZONE_RECLAIM_LOCKED)) + return 0; + ret = __zone_reclaim(zone, gfp_mask, order); + zone_clear_flag(zone, ZONE_RECLAIM_LOCKED); + + return ret; } #endif |