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SubjectRe: [v3 PATCH 1/2] mm: vmscan: remove double slab pressure by inc'ing sc->nr_scanned
On Tue, May 21, 2019 at 05:40:41PM +0800, Yang Shi wrote:
> The commit 9092c71bb724 ("mm: use sc->priority for slab shrink targets")
> has broken up the relationship between sc->nr_scanned and slab pressure.
> The sc->nr_scanned can't double slab pressure anymore. So, it sounds no
> sense to still keep sc->nr_scanned inc'ed. Actually, it would prevent
> from adding pressure on slab shrink since excessive sc->nr_scanned would
> prevent from scan->priority raise.
>
> The bonnie test doesn't show this would change the behavior of
> slab shrinkers.
>
> w/ w/o
> /sec %CP /sec %CP
> Sequential delete: 3960.6 94.6 3997.6 96.2
> Random delete: 2518 63.8 2561.6 64.6
>
> The slight increase of "/sec" without the patch would be caused by the
> slight increase of CPU usage.
>
> Cc: Josef Bacik <josef@toxicpanda.com>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

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