On Tue 28-06-11 17:06:49, KAMEZAWA Hiroyuki wrote:

On Tue, 28 Jun 2011 10:08:47 +0200
Michal Hocko [off-list ref] wrote:

quoted

I am sorry, that I am answering that late but I didn't get to this
sooner.

On Mon 27-06-11 16:18:12, Andrew Morton wrote:

quoted

From: KAMEZAWA Hiroyuki <redacted>

commit d149e3b ("memcg: add the soft_limit reclaim in global direct
reclaim") adds a softlimit hook to shrink_zones().  By this, soft limit is
called as

   try_to_free_pages()
       do_try_to_free_pages()
           shrink_zones()
               mem_cgroup_soft_limit_reclaim()

Then, direct reclaim is memcg softlimit hint aware, now.

But, the memory cgroup's "limit" path can call softlimit shrinker.

   try_to_free_mem_cgroup_pages()
       do_try_to_free_pages()
           shrink_zones()
               mem_cgroup_soft_limit_reclaim()

This will cause a global reclaim when a memcg hits limit.

Sorry, I do not get it. How does it cause the global reclaim? Did you
mean soft reclaim?

yes. soft reclaim does global reclaim (in some means). 

But calling it global reclaim is rather confusing because in both paths
we have sc.mem_cgroup set to non-NULL which is evaluated as
!scanning_global_lru(sc). Anyway, this is not that important, I just
wanted to be sure what you meant by that comment.

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic

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