path: root/mm
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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 /mm
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 'mm')
3 files changed, 5 insertions, 25 deletions
diff --git a/mm/internal.h b/mm/internal.h
index 612c14f5e0f..29e1e761f9e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -83,7 +83,6 @@ extern unsigned long highest_memmap_pfn;
extern int isolate_lru_page(struct page *page);
extern void putback_lru_page(struct page *page);
-extern unsigned long zone_reclaimable_pages(struct zone *zone);
extern bool zone_reclaimable(struct zone *zone);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 61119b8a11e..2d30e2cfe80 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -205,7 +205,8 @@ static unsigned long zone_dirtyable_memory(struct zone *zone)
nr_pages = zone_page_state(zone, NR_FREE_PAGES);
nr_pages -= min(nr_pages, zone->dirty_balance_reserve);
- nr_pages += zone_reclaimable_pages(zone);
+ nr_pages += zone_page_state(zone, NR_INACTIVE_FILE);
+ nr_pages += zone_page_state(zone, NR_ACTIVE_FILE);
return nr_pages;
@@ -258,7 +259,8 @@ static unsigned long global_dirtyable_memory(void)
x = global_page_state(NR_FREE_PAGES);
x -= min(x, dirty_balance_reserve);
- x += global_reclaimable_pages();
+ x += global_page_state(NR_INACTIVE_FILE);
+ x += global_page_state(NR_ACTIVE_FILE);
if (!vm_highmem_is_dirtyable)
x -= highmem_dirtyable_memory(x);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 90c4075d8d7..a9c74b40968 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -147,7 +147,7 @@ static bool global_reclaim(struct scan_control *sc)
-unsigned long zone_reclaimable_pages(struct zone *zone)
+static unsigned long zone_reclaimable_pages(struct zone *zone)
int nr;
@@ -3315,27 +3315,6 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
- * The reclaimable count would be mostly accurate.
- * The less reclaimable pages may be
- * - mlocked pages, which will be moved to unevictable list when encountered
- * - mapped pages, which may require several travels to be reclaimed
- * - dirty pages, which is not "instantly" reclaimable
- */
-unsigned long global_reclaimable_pages(void)
- int nr;
- nr = global_page_state(NR_ACTIVE_FILE) +
- global_page_state(NR_INACTIVE_FILE);
- if (get_nr_swap_pages() > 0)
- nr += global_page_state(NR_ACTIVE_ANON) +
- global_page_state(NR_INACTIVE_ANON);
- return nr;
* Try to free `nr_to_reclaim' of memory, system-wide, and return the number of