linux-kernel - Re: [RFC] Making memcg track ownership per address_space or anon

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Message-ID: <20150211223030.GB12728@htj.duckdns.org>
Date:	Wed, 11 Feb 2015 17:30:30 -0500
From:	Tejun Heo <tj@...nel.org>
To:	Konstantin Khlebnikov <koct9i@...il.com>
Cc:	Greg Thelen <gthelen@...gle.com>,
	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.cz>,
	Cgroups <cgroups@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Jan Kara <jack@...e.cz>, Dave Chinner <david@...morbit.com>,
	Jens Axboe <axboe@...nel.dk>,
	Christoph Hellwig <hch@...radead.org>,
	Li Zefan <lizefan@...wei.com>, Hugh Dickins <hughd@...gle.com>
Subject: Re: [RFC] Making memcg track ownership per address_space or anon_vma

Hello,

On Thu, Feb 12, 2015 at 02:15:29AM +0400, Konstantin Khlebnikov wrote:
> Well, ok. Even if shared writes are rare whey should be handled somehow
> without relying on kupdate-like writeback. If memcg has a lot of dirty pages

This only works iff we consider those cases to be marginal enough to
be handle them in a pretty ghetto way.

> but their inodes are accidentially belong to wrong wb queues when tasks in
> that memcg shouldn't stuck in balance-dirty-pages until somebody outside
> acidentially writes this data. That's all what I wanted to say.

But, right, yeah, corner cases around this could be nasty if writeout
interval is set really high.  I don't think it matters for the default
5s interval at all.  Maybe what we need is queueing a delayed per-wb
work w/ the default writeout interval when dirtying a foreign inode.
I'll think more about it.

Thanks.

-- 
tejun
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