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authorMichal Hocko <mhocko@suse.cz>2015-02-11 15:28:24 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-11 17:06:07 -0800
commitba4877b9ca51f80b5d30f304a46762f0509e1635 (patch)
tree9c777e79a952583dd33f53687e692056c5e33a7b /mm/vmstat.c
parent9c0415eb8cbf0c8fd043b6c0f0354308ab099df5 (diff)
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vmstat: do not use deferrable delayed work for vmstat_update
Vinayak Menon has reported that an excessive number of tasks was throttled in the direct reclaim inside too_many_isolated() because NR_ISOLATED_FILE was relatively high compared to NR_INACTIVE_FILE. However it turned out that the real number of NR_ISOLATED_FILE was 0 and the per-cpu vm_stat_diff wasn't transferred into the global counter. vmstat_work which is responsible for the sync is defined as deferrable delayed work which means that the defined timeout doesn't wake up an idle CPU. A CPU might stay in an idle state for a long time and general effort is to keep such a CPU in this state as long as possible which might lead to all sorts of troubles for vmstat consumers as can be seen with the excessive direct reclaim throttling. This patch basically reverts 39bf6270f524 ("VM statistics: Make timer deferrable") but it shouldn't cause any problems for idle CPUs because only CPUs with an active per-cpu drift are woken up since 7cc36bbddde5 ("vmstat: on-demand vmstat workers v8") and CPUs which are idle for a longer time shouldn't have per-cpu drift. Fixes: 39bf6270f524 (VM statistics: Make timer deferrable) Signed-off-by: Michal Hocko <mhocko@suse.cz> Reported-by: Vinayak Menon <vinmenon@codeaurora.org> Acked-by: Christoph Lameter <cl@linux.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: 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/vmstat.c')
-rw-r--r--mm/vmstat.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 9943e5fd74e6..470cdd5b924b 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1452,7 +1452,7 @@ static void __init start_shepherd_timer(void)
int cpu;
for_each_possible_cpu(cpu)
- INIT_DEFERRABLE_WORK(per_cpu_ptr(&vmstat_work, cpu),
+ INIT_DELAYED_WORK(per_cpu_ptr(&vmstat_work, cpu),
vmstat_update);
if (!alloc_cpumask_var(&cpu_stat_off, GFP_KERNEL))