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From: Greg Thelen <gthelen@google.com>
To: Wu Fengguang <fengguang.wu@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	linux-mm@kvack.org, "hannes@cmpxchg.org" <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@suse.cz>,
	"bsingharora@gmail.com" <bsingharora@gmail.com>,
	Hugh Dickins <hughd@google.com>, Ying Han <yinghan@google.com>,
	Mel Gorman <mgorman@suse.de>
Subject: Re: memcg writeback (was Re: [Lsf-pc] [LSF/MM TOPIC] memcg topics.)
Date: Thu, 9 Feb 2012 21:52:03 -0800	[thread overview]
Message-ID: <CAHH2K0bmZn-hthrMasw8FdmgERct2m-8gwsumXpV1q=WQzUW1A@mail.gmail.com> (raw)
In-Reply-To: <CAHH2K0bmURXpk6-4D9q7ErppVyMJjKMsn37MenwqcP_nnT66Mw@mail.gmail.com>

(removed lsf-pc@lists.linux-foundation.org because this really isn't
program committee matter)

On Wed, Feb 1, 2012 at 11:52 PM, Wu Fengguang <fengguang.wu@intel.com> wrote:
> Unfortunately the memcg partitioning could fundamentally make the
> dirty throttling more bumpy.
>
> Imagine 10 memcgs each with
>
> - memcg_dirty_limit=50MB
> - 1 dd dirty task
>
> The flusher thread will be working on 10 inodes in turn, each time
> grabbing the next inode and taking ~0.5s to write ~50MB of its dirty
> pages to the disk. So each inode will be flushed on every ~5s.

Does the flusher thread need to write 50MB/inode in this case?  Would
there be problems interleaving writes by declaring some max write
limit (e.g. 8 MiB/write).  Such interleaving would be beneficial if
there are multiple memcg expecting service from the single bdi flusher
thread.  I suspect certain filesystems might have increased
fragmentation with this, but I am not sure if appending writes can
easily expand an extent.

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  reply	other threads:[~2012-02-10  5:52 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-02-08  7:55 memcg writeback (was Re: [Lsf-pc] [LSF/MM TOPIC] memcg topics.) Greg Thelen
2012-02-08  9:31 ` Wu Fengguang
2012-02-08 20:54   ` Ying Han
2012-02-09 13:50     ` Wu Fengguang
2012-02-13 18:40       ` Ying Han
2012-02-10  5:51   ` Greg Thelen
2012-02-10  5:52     ` Greg Thelen [this message]
2012-02-10  9:20       ` Wu Fengguang
2012-02-10 11:47     ` Wu Fengguang
2012-02-11 12:44       ` reclaim the LRU lists full of dirty/writeback pages Wu Fengguang
2012-02-11 14:55         ` Rik van Riel
2012-02-12  3:10           ` Wu Fengguang
2012-02-12  6:45             ` Wu Fengguang
2012-02-13 15:43             ` Jan Kara
2012-02-14 10:03               ` Wu Fengguang
2012-02-14 13:29                 ` Jan Kara
2012-02-16  4:00                   ` Wu Fengguang
2012-02-16 12:44                     ` Jan Kara
2012-02-16 13:32                       ` Wu Fengguang
2012-02-16 14:06                         ` Wu Fengguang
2012-02-17 16:41                     ` Wu Fengguang
2012-02-20 14:00                       ` Jan Kara
2012-02-14 10:19         ` Mel Gorman
2012-02-14 13:18           ` Wu Fengguang
2012-02-14 13:35             ` Wu Fengguang
2012-02-14 15:51             ` Mel Gorman
2012-02-16  9:50               ` Wu Fengguang
2012-02-16 17:31                 ` Mel Gorman
2012-02-27 14:24                   ` Fengguang Wu
2012-02-16  0:00             ` KAMEZAWA Hiroyuki
2012-02-16  3:04               ` Wu Fengguang
2012-02-16  3:52                 ` KAMEZAWA Hiroyuki
2012-02-16  4:05                   ` Wu Fengguang

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