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From: Johannes Weiner <hannes@cmpxchg.org>
To: Michal Hocko <mhocko@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Glauber Costa <glommer@parallels.com>,
	linux-mm@kvack.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
	Li Zefan <lizefan@huawei.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Balbir Singh <bsingharora@gmail.com>
Subject: Re: [PATCH v3 3/6] memcg: Simplify mem_cgroup_force_empty_list error handling
Date: Wed, 14 Nov 2012 13:33:30 -0500	[thread overview]
Message-ID: <20121114183330.GA32421@cmpxchg.org> (raw)
In-Reply-To: <20121114135930.GE4929@dhcp22.suse.cz>

On Wed, Nov 14, 2012 at 02:59:30PM +0100, Michal Hocko wrote:
> On Tue 13-11-12 16:10:41, Johannes Weiner wrote:
> > Would it make sense to stick a wait_on_page_locked() in there just so
> > that we don't busy spin on a page under migration/reclaim?
> 
> Hmm, this would also mean that get_page_unless_zero would fail as well
> and so we would schedule in mem_cgroup_force_empty_list. It is true that
> there might be no other runnable task so we can busy loop so yes this
> would help. Care to cook the patch?

Eventually get_page_unless_zero() would fail but we could still spin
on a page while it's off the LRU and migration performs writeback on
it e.g.  cond_resched() does not necessarily schedule just because
there is another runnable task, I think, it's voluntary preemption
when the task needs rescheduling anyway, not yield.

Maybe not worth bothering...

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  reply	other threads:[~2012-11-14 18:33 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-26 11:37 memcg/cgroup: do not fail fail on pre_destroy callbacks Michal Hocko
2012-10-26 11:37 ` [PATCH v3 1/6] memcg: split mem_cgroup_force_empty into reclaiming and reparenting parts Michal Hocko
2012-10-29 13:45   ` Glauber Costa
2012-10-31 16:29   ` Johannes Weiner
2012-10-26 11:37 ` [PATCH v3 2/6] memcg: root_cgroup cannot reach mem_cgroup_move_parent Michal Hocko
2012-10-29 13:48   ` Glauber Costa
2012-10-29 13:52     ` Michal Hocko
2012-10-31 16:31   ` Johannes Weiner
2012-10-26 11:37 ` [PATCH v3 3/6] memcg: Simplify mem_cgroup_force_empty_list error handling Michal Hocko
2012-10-29 13:58   ` Glauber Costa
2012-10-29 14:15     ` Michal Hocko
2012-10-29 15:09       ` Glauber Costa
2012-10-29 22:00     ` Andrew Morton
2012-10-30 10:35       ` Michal Hocko
2012-10-31 21:30         ` Andrew Morton
2012-11-13 21:10         ` Johannes Weiner
2012-11-14 13:59           ` Michal Hocko
2012-11-14 18:33             ` Johannes Weiner [this message]
2012-10-26 11:37 ` [PATCH v3 4/6] cgroups: forbid pre_destroy callback to fail Michal Hocko
2012-10-29 14:04   ` Glauber Costa
2012-10-29 14:06     ` Glauber Costa
2012-10-29 14:17       ` Michal Hocko
2012-11-13 21:13   ` Johannes Weiner
2012-10-26 11:37 ` [PATCH v3 5/6] memcg: make mem_cgroup_reparent_charges non failing Michal Hocko
2012-10-29 14:07   ` Glauber Costa
2012-10-26 11:37 ` [PATCH v3 6/6] hugetlb: do not fail in hugetlb_cgroup_pre_destroy Michal Hocko
2012-10-29 14:08   ` Glauber Costa
2012-10-29 23:26 ` memcg/cgroup: do not fail fail on pre_destroy callbacks Tejun Heo
2012-10-30 23:37   ` Michal Hocko

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