Re: [PATCH] Revert "mm: vmscan: fix misused nr_reclaimed in shrink_mem_cgroup_zone()"

[Hillf Danton <dhillf@gmail.com>]

On Wed, Apr 11, 2012 at 12:44 AM, Ying Han <yinghan@google.com> wrote:
>
> There are two places where we do early break out in direct reclaim path.
>
> 1. For each priority loop after calling shrink_zones(), we check
> (sc->nr_reclaimed >= sc->nr_to_reclaim)
>
> 2. For each memcg reclaim (shrink_mem_cgroup_zone) under
> shrink_zone(), we check (nr_reclaimed >= nr_to_reclaim)
>
> The second one says "if 32 (nr_to_reclaim) pages being reclaimed from
> this memcg under high priority, break". This check is necessary here
> to prevent over pressure each memcg under shrink_zone().
>
> Regarding the reverted patch, it tries to convert the "nr_reclaimed"
> to "total_reclaimed" for outer loop (restart). First of all, it
> changes the logic by doing less work each time
> should_continue_reclaim() is true. Second, the fix is simply broken by
> decrementing nr_to_reclaim each time.
>
Got, thanks:)

-hd

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