Re: [PATCH] mm/vmstat: retrieve more accurate vmstat value

From: Joonsoo Kim
Date: Wed Nov 25 2015 - 20:55:47 EST


On Wed, Nov 25, 2015 at 01:00:22PM +0100, Michal Hocko wrote:
> On Tue 24-11-15 15:22:03, Joonsoo Kim wrote:
> > When I tested compaction in low memory condition, I found that
> > my benchmark is stuck in congestion_wait() at shrink_inactive_list().
> > This stuck last for 1 sec and after then it can escape. More investigation
> > shows that it is due to stale vmstat value. vmstat is updated every 1 sec
> > so it is stuck for 1 sec.
>
> Wouldn't it be sufficient to use zone_page_state_snapshot in
> too_many_isolated?

Yes, it would work in this case. But, I prefer this patch because
all zone_page_state() users get this benefit.

Thanks.
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