Re: [PATCH] memcg: remove mem_cgroup_reclaimable check from soft reclaim

[Johannes Weiner]

On Tue, Oct 21, 2014 at 05:15:50PM +0400, Vladimir Davydov wrote:
> mem_cgroup_reclaimable() checks whether a cgroup has reclaimable pages
> on *any* NUMA node. However, the only place where it's called is
> mem_cgroup_soft_reclaim(), which tries to reclaim memory from a
> *specific* zone. So the way how it's used is incorrect - it will return
> true even if the cgroup doesn't have pages on the zone we're scanning.
> 
> I think we can get rid of this check completely, because
> mem_cgroup_shrink_node_zone(), which is called by
> mem_cgroup_soft_reclaim() if mem_cgroup_reclaimable() returns true, is
> equivalent to shrink_lruvec(), which exits almost immediately if the
> lruvec passed to it is empty. So there's no need to optimize anything
> here. Besides, we don't have such a check in the general scan path
> (shrink_zone) either.
> 
> Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>

How about this on top?

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