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authorJohannes Weiner <hannes@cmpxchg.org>2014-01-29 14:05:41 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-29 16:22:39 -0800
commita1c3bfb2f67ef766de03f1f56bdfff9c8595ab14 (patch)
treee06405192d674561bf2718ab03879c32103ae34e /include
parenta804552b9a15c931cfc2a92a2e0aed1add8b580a (diff)
mm/page-writeback.c: do not count anon pages as dirtyable memory
The VM is currently heavily tuned to avoid swapping. Whether that is good or bad is a separate discussion, but as long as the VM won't swap to make room for dirty cache, we can not consider anonymous pages when calculating the amount of dirtyable memory, the baseline to which dirty_background_ratio and dirty_ratio are applied. A simple workload that occupies a significant size (40+%, depending on memory layout, storage speeds etc.) of memory with anon/tmpfs pages and uses the remainder for a streaming writer demonstrates this problem. In that case, the actual cache pages are a small fraction of what is considered dirtyable overall, which results in an relatively large portion of the cache pages to be dirtied. As kswapd starts rotating these, random tasks enter direct reclaim and stall on IO. Only consider free pages and file pages dirtyable. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Reported-by: Tejun Heo <tj@kernel.org> Tested-by: Tejun Heo <tj@kernel.org> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Wu Fengguang <fengguang.wu@intel.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/vmstat.h2
1 files changed, 0 insertions, 2 deletions
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index e4b948080d20..a67b38415768 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -142,8 +142,6 @@ static inline unsigned long zone_page_state_snapshot(struct zone *zone,
return x;
}
-extern unsigned long global_reclaimable_pages(void);
-
#ifdef CONFIG_NUMA
/*
* Determine the per node value of a stat item. This function