Re: [PATCH] mm, memcg: add workingset_restore in memory.stat

[Johannes Weiner <hannes@cmpxchg.org>]

On Sat, May 02, 2020 at 10:18:49AM -0400, Yafang Shao wrote:
> There's a new workingset counter introduced in commit 1899ad18c607 ("mm:
> workingset: tell cache transitions from workingset thrashing"). With the
> help of this counter we can know the workingset is transitioning or
> thrashing. To leverage the benifit of this counter to memcg, we should
> introduce it into memory.stat. Then we could know the workingset of the
> workload inside a memcg better.
> 
> Bellow is the verification of this new counter in memory.stat.
>
> Read a file into the memory and then read it again to make these pages be
> active. The size of this file is 1G. (memory.max is greater than file size)
> The counters in memory.stat will be,
> 	inactive_file 0
> 	active_file 1073639424
> 
> 	workingset_refault 0
> 	workingset_activate 0
> 	workingset_restore 0
> 	workingset_nodereclaim 0
> Trigger the memcg reclaim by setting a lower value to memory.high, and
> then some pages will be demoted into inactive list, and then some pages
> in the inactive list will be evicted into the storage.
> 	inactive_file 498094080
> 	active_file 310063104
> 
> 	workingset_refault 0
> 	workingset_activate 0
> 	workingset_restore 0
> 	workingset_nodereclaim 0
> Then recover the memory.high and read the file into memory again. As a
> result of it, the transitioning will occur. Bellow is the result of this
> transitioning,
> 	inactive_file 498094080
> 	active_file 575397888
> 
> 	workingset_refault 64746
> 	workingset_activate 64746
> 	workingset_restore 64746
> 	workingset_nodereclaim 0
> 
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>

Thanks, yes, I've missed that counter a few times while debugging
something but never gotten around to actually adding it.

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