The patch titled
Subject: mm: use global_dirty_limit in throttle_vm_writeout()
has been added to the -mm tree. Its filename is
mm-use-global_dirty_limit-in-throttle_vm_writeout.patch
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From: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Subject: 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@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Ying Han <yinghan@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page-writeback.c | 1 +
1 file changed, 1 insertion(+)
diff -puN mm/page-writeback.c~mm-use-global_dirty_limit-in-throttle_vm_writeout mm/page-writeback.c
--- a/mm/page-writeback.c~mm-use-global_dirty_limit-in-throttle_vm_writeout
+++ a/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
_
Subject: Subject: mm: use global_dirty_limit in throttle_vm_writeout()
Patches currently in -mm which might be from fengguang.wu@xxxxxxxxx are
linux-next.patch
pagemap-avoid-splitting-thp-when-reading-proc-pid-pagemap.patch
thp-optimize-away-unnecessary-page-table-locking.patch
thp-optimize-away-unnecessary-page-table-locking-fix.patch
pagemap-export-kpf_thp.patch
pagemap-document-kpf_thp-and-make-page-types-aware-of-it.patch
pagemap-introduce-data-structure-for-pagemap-entry.patch
mm-dont-set-__gfp_write-on-ramfs-sysfs-writes.patch
mm-use-global_dirty_limit-in-throttle_vm_writeout.patch
move-page-typesc-from-documentation-to-tools-vm.patch
move-slabinfoc-to-tools-vm.patch
move-hugepage-test-examples-to-tools-testing-selftests-vm.patch
move-hugepage-test-examples-to-tools-testing-selftests-vm-fix.patch
move-hugepage-test-examples-to-tools-testing-selftests-vm-fix-fix.patch
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