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authorFengguang Wu <fengguang.wu@intel.com>2012-03-21 16:34:09 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 17:54:58 -0700
commit47a133339c332f9f8e155c70f5da401aded69948 (patch)
tree94f8fb512ebe8e29d0a3f11a04b04004afd4ab59 /mm/page-writeback.c
parent1010bb1b80edb0713415dfe1f97114d320f58c4f (diff)
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mm: use global_dirty_limit in throttle_vm_writeout()
When starting a memory hog task, a desktop box w/o swap is found to go unresponsive for a long time. It's solely caused by lots of congestion waits in throttle_vm_writeout(): gnome-system-mo-4201 553.073384: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1 gnome-system-mo-4201 553.073386: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000 gtali-4237 553.080377: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1 gtali-4237 553.080378: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000 Xorg-3483 553.103375: congestion_wait: throttle_vm_writeout+0x70/0x7f shrink_mem_cgroup_zone+0x48f/0x4a1 Xorg-3483 553.103377: writeback_congestion_wait: usec_timeout=100000 usec_delayed=100000 The root cause is, the dirty threshold is knocked down a lot by the memory hog task. Fixed by using global_dirty_limit which decreases gradually on such events and can guarantee we stay above (the also decreasing) nr_dirty in the progress of following down to the new dirty threshold. Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jan Kara <jack@suse.cz> Cc: Greg Thelen <gthelen@google.com> Cc: Ying Han <yinghan@google.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page-writeback.c')
-rw-r--r--mm/page-writeback.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 363ba7082ef5..3fc261705b1e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -1472,6 +1472,7 @@ void throttle_vm_writeout(gfp_t gfp_mask)
for ( ; ; ) {
global_dirty_limits(&background_thresh, &dirty_thresh);
+ dirty_thresh = hard_dirty_limit(dirty_thresh);
/*
* Boost the allowable dirty threshold a bit for page