From: Glauber Costa <glommer@parallels.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Ying Han <yinghan@google.com>, Tejun Heo <htejun@gmail.com>,
Li Zefan <lizefan@huawei.com>
Subject: Re: [patch v2 3/6] memcg: rework mem_cgroup_iter to use cgroup iterators
Date: Wed, 28 Nov 2012 13:23:57 +0400 [thread overview]
Message-ID: <50B5D82D.6010109@parallels.com> (raw)
In-Reply-To: <20121128091745.GC12309@dhcp22.suse.cz>
On 11/28/2012 01:17 PM, Michal Hocko wrote:
> On Wed 28-11-12 17:47:59, KAMEZAWA Hiroyuki wrote:
>> (2012/11/27 3:47), Michal Hocko wrote:
> [...]
>>> + /*
>>> + * Even if we found a group we have to make sure it is alive.
>>> + * css && !memcg means that the groups should be skipped and
>>> + * we should continue the tree walk.
>>> + * last_visited css is safe to use because it is protected by
>>> + * css_get and the tree walk is rcu safe.
>>> + */
>>> + if (css == &root->css || (css && css_tryget(css)))
>>> + memcg = mem_cgroup_from_css(css);
>>
>> Could you note that this iterator will never visit dangling(removed)
>> memcg, somewhere ?
>
> OK, I can add it to the function comment but the behavior hasn't changed
> so I wouldn't like to confuse anybody.
>
>> Hmm, I'm not sure but it may be trouble at shrkinking dangling
>> kmem_cache(slab).
>
> We do not shrink slab at all.
yet. However...
> Those objects that are in a dead memcg
> wait for their owner tho release them which will make the dangling group
> eventually go away
>
>>
>> Costa, how do you think ?
>>
In general, I particularly believe it is a good idea to skip dead memcgs
in the iterator. I don't anticipate any problems with shrinking at all.
Basically, we will only ever actively shrink when the memcg is dying, at
which point it is still alive.
After this, it's better to just leave it to vmscan. Whenever there is
pressure, it will go away.
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next prev parent reply other threads:[~2012-11-28 9:24 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-26 18:47 rework mem_cgroup iterator Michal Hocko
2012-11-26 18:47 ` [patch v2 1/6] memcg: synchronize per-zone iterator access by a spinlock Michal Hocko
2012-11-26 18:47 ` [patch v2 2/6] memcg: keep prev's css alive for the whole mem_cgroup_iter Michal Hocko
2012-11-28 8:38 ` Kamezawa Hiroyuki
2012-11-26 18:47 ` [patch v2 3/6] memcg: rework mem_cgroup_iter to use cgroup iterators Michal Hocko
2012-11-28 8:47 ` Kamezawa Hiroyuki
2012-11-28 9:17 ` Michal Hocko
2012-11-28 9:23 ` Glauber Costa [this message]
2012-11-28 9:33 ` Michal Hocko
2012-11-28 9:35 ` Glauber Costa
2012-11-30 4:07 ` Kamezawa Hiroyuki
2012-12-07 3:39 ` Ying Han
2012-12-07 3:43 ` Ying Han
2012-12-07 8:58 ` Michal Hocko
2012-12-07 17:12 ` Ying Han
2012-12-07 17:27 ` Michal Hocko
2012-12-07 19:16 ` Ying Han
2012-12-07 19:35 ` Michal Hocko
2012-12-07 9:01 ` Michal Hocko
2012-12-09 16:59 ` Ying Han
2012-12-11 15:50 ` Michal Hocko
2012-12-11 16:15 ` Michal Hocko
2012-12-11 18:10 ` Michal Hocko
2012-12-11 22:43 ` Ying Han
2012-12-12 8:55 ` Michal Hocko
2012-12-12 17:57 ` Ying Han
2012-12-12 18:08 ` Michal Hocko
2012-12-11 22:31 ` Ying Han
2012-12-09 19:39 ` Ying Han
2012-12-11 15:54 ` Michal Hocko
2012-12-11 22:36 ` Ying Han
2012-12-12 9:06 ` Michal Hocko
2012-12-12 18:09 ` Ying Han
2012-12-12 18:34 ` Michal Hocko
2012-12-12 18:42 ` Michal Hocko
2012-12-14 1:06 ` Ying Han
2012-12-14 10:56 ` [PATCH] memcg,vmscan: do not break out targeted reclaim without reclaimed pages Michal Hocko
2012-12-12 19:24 ` [patch v2 3/6] memcg: rework mem_cgroup_iter to use cgroup iterators Michal Hocko
2012-12-14 1:14 ` Ying Han
2012-12-14 12:07 ` Michal Hocko
2012-12-14 23:08 ` Ying Han
2012-12-14 12:37 ` Michal Hocko
2012-11-26 18:47 ` [patch v2 4/6] memcg: simplify mem_cgroup_iter Michal Hocko
2012-11-28 8:52 ` Kamezawa Hiroyuki
2012-11-30 4:09 ` Kamezawa Hiroyuki
2012-12-09 17:01 ` Ying Han
2012-12-11 15:57 ` Michal Hocko
2012-12-11 4:35 ` Ying Han
2012-12-11 16:01 ` Michal Hocko
2012-12-11 22:52 ` Ying Han
2012-11-26 18:47 ` [patch v2 5/6] memcg: further " Michal Hocko
2012-11-30 4:10 ` Kamezawa Hiroyuki
2012-11-30 9:08 ` Glauber Costa
2012-11-30 10:23 ` Michal Hocko
2012-11-26 18:47 ` [patch v2 6/6] cgroup: remove css_get_next Michal Hocko
2012-11-30 4:12 ` Kamezawa Hiroyuki
2012-11-30 8:18 ` Michal Hocko
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