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From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
To: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: balbir@linux.vnet.ibm.com, linux-mm@kvack.org,
	Andrea Righi <arighi@develer.com>,
	linux-kernel@vger.kernel.org,
	Trond Myklebust <trond.myklebust@fys.uio.no>,
	Suleiman Souhlal <suleiman@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	containers@lists.linux-foundation.org,
	Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH mmotm 2.5/4] memcg: disable irq at page cgroup lock (Re: [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting infrastructure)
Date: Thu, 11 Mar 2010 14:13:00 +0900	[thread overview]
Message-ID: <20100311141300.90b85391.kamezawa.hiroyu@jp.fujitsu.com> (raw)
In-Reply-To: <20100311135847.990eee62.nishimura@mxp.nes.nec.co.jp>

On Thu, 11 Mar 2010 13:58:47 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:
> > I'll consider yet another fix for race in account migration if I can.
> > 
> me too.
> 

How about this ? Assume that the race is very rare.

	1. use trylock when updating statistics.
	   If trylock fails, don't account it.

	2. add PCG_FLAG for all status as

+	PCG_ACCT_FILE_MAPPED, /* page is accounted as file rss*/
+	PCG_ACCT_DIRTY, /* page is dirty */
+	PCG_ACCT_WRITEBACK, /* page is being written back to disk */
+	PCG_ACCT_WRITEBACK_TEMP, /* page is used as temporary buffer for FUSE */
+	PCG_ACCT_UNSTABLE_NFS, /* NFS page not yet committed to the server */

	3. At reducing counter, check PCG_xxx flags by
	TESTCLEARPCGFLAG()

This is similar to an _used_ method of LRU accounting. And We can think this
method's error-range never go too bad number. 

I think this kind of fuzzy accounting is enough for writeback status.
Does anyone need strict accounting ?

Thanks,
-Kame

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  reply	other threads:[~2010-03-11  5:16 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-07 20:57 [PATCH -mmotm 0/4] memcg: per cgroup dirty limit (v5) Andrea Righi
2010-03-07 20:57 ` [PATCH -mmotm 1/4] memcg: dirty memory documentation Andrea Righi
2010-03-07 20:57 ` [PATCH -mmotm 2/4] page_cgroup: introduce file cache flags Andrea Righi
2010-03-07 20:57 ` [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting infrastructure Andrea Righi
2010-03-08  1:44   ` Daisuke Nishimura
2010-03-08  1:56     ` KAMEZAWA Hiroyuki
2010-03-08  2:17       ` Daisuke Nishimura
2010-03-08  2:37         ` KAMEZAWA Hiroyuki
2010-03-08  8:07           ` Daisuke Nishimura
2010-03-08  8:31             ` KAMEZAWA Hiroyuki
2010-03-09  0:12               ` Andrea Righi
2010-03-09  0:19                 ` KAMEZAWA Hiroyuki
2010-03-09  1:29                   ` [PATCH mmotm 2.5/4] memcg: disable irq at page cgroup lock (Re: [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting infrastructure) Daisuke Nishimura
2010-03-09  2:07                     ` KAMEZAWA Hiroyuki
2010-03-09  4:50                     ` Balbir Singh
2010-03-10  1:43                       ` Daisuke Nishimura
2010-03-10  3:56                         ` Balbir Singh
2010-03-11  4:31                           ` Daisuke Nishimura
2010-03-11  4:49                             ` KAMEZAWA Hiroyuki
2010-03-11  4:58                               ` Daisuke Nishimura
2010-03-11  5:13                                 ` KAMEZAWA Hiroyuki [this message]
2010-03-11  6:15                                   ` KAMEZAWA Hiroyuki
2010-03-11  7:50                                     ` Daisuke Nishimura
2010-03-11  8:06                                       ` KAMEZAWA Hiroyuki
2010-03-11 16:54                               ` Vivek Goyal
2010-03-11 22:34                                 ` Andrea Righi
2010-03-11 23:46                                 ` KAMEZAWA Hiroyuki
2010-03-09  9:07                     ` Andrea Righi
2010-03-09  0:18               ` [PATCH -mmotm 3/4] memcg: dirty pages accounting and limiting infrastructure Daisuke Nishimura
2010-03-09  0:20                 ` KAMEZAWA Hiroyuki
2010-03-09  0:52                   ` Daisuke Nishimura
2010-03-09  0:03             ` Andrea Righi
2010-03-07 20:57 ` [PATCH -mmotm 4/4] memcg: dirty pages instrumentation Andrea Righi
2010-03-08  2:31   ` KAMEZAWA Hiroyuki

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