From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>, Wu Fengguang <fengguang.wu@intel.com>,
linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Dave Chinner <david@fromorbit.com>,
Greg Thelen <gthelen@google.com>,
Minchan Kim <minchan.kim@gmail.com>,
Vivek Goyal <vgoyal@redhat.com>,
Andrea Righi <arighi@develer.com>, linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 17/18] writeback: fix dirtied pages accounting on redirty
Date: Wed, 07 Sep 2011 10:19:47 +0200 [thread overview]
Message-ID: <1315383587.11101.18.camel@twins> (raw)
In-Reply-To: <20110907065635.GA12619@lst.de>
On Wed, 2011-09-07 at 08:56 +0200, Christoph Hellwig wrote:
> On Wed, Sep 07, 2011 at 02:22:22AM +0200, Jan Kara wrote:
> > > So wtf is ext4 doing? Shouldn't a page stay dirty until its written out?
> > >
> > > That is, should we really frob around this behaviour or fix ext4 because
> > > its on crack?
> > Fengguang, could you please verify your findings with recent kernel? I
> > believe ext4 got fixed in this regard some time ago already (and yes, old
> > delalloc writeback code in ext4 was terrible).
>
> The pattern we do in writeback is:
>
> in pageout / write_cache_pages:
> lock_page();
> clear_page_dirty_for_io();
>
> in ->writepage:
> set_page_writeback();
> unlock_page();
> end_page_writeback();
>
> So whenever ->writepage decides it doesn't want to write things back
> we have to redirty pages. We have this happen quite a bit in every
> filesystem, but ext4 hits it a lot more than usual because it refuses
> to write out delalloc pages from plain ->writepage and only allows
> ->writepages to do it.
Ah, right, so it is a fairly common thing and not something easily fixed
in filesystems.
Ok so I guess the patch is good. Thanks!
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next prev parent reply other threads:[~2011-09-07 8:19 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-04 1:53 [PATCH 00/18] IO-less dirty throttling v11 Wu Fengguang
2011-09-04 1:53 ` [PATCH 01/18] writeback: account per-bdi accumulated dirtied pages Wu Fengguang
2011-09-04 1:53 ` [PATCH 02/18] writeback: dirty position control Wu Fengguang
2011-09-05 15:02 ` Peter Zijlstra
2011-09-06 2:10 ` Wu Fengguang
2011-09-05 15:05 ` Peter Zijlstra
2011-09-06 2:43 ` Wu Fengguang
2011-09-06 18:20 ` Vivek Goyal
2011-09-08 2:53 ` Wu Fengguang
2011-11-12 5:44 ` Nai Xia
2011-09-04 1:53 ` [PATCH 03/18] writeback: dirty rate control Wu Fengguang
2011-09-29 11:57 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 04/18] writeback: stabilize bdi->dirty_ratelimit Wu Fengguang
2011-09-04 1:53 ` [PATCH 05/18] writeback: per task dirty rate limit Wu Fengguang
2011-09-06 15:47 ` Peter Zijlstra
2011-09-06 23:27 ` Jan Kara
2011-09-06 23:34 ` Jan Kara
2011-09-07 7:27 ` Peter Zijlstra
2011-09-07 1:04 ` Wu Fengguang
2011-09-07 7:31 ` Peter Zijlstra
2011-09-07 11:00 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 06/18] writeback: IO-less balance_dirty_pages() Wu Fengguang
2011-09-06 12:13 ` Peter Zijlstra
2011-09-07 2:46 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 07/18] writeback: dirty ratelimit - think time compensation Wu Fengguang
2011-09-04 1:53 ` [PATCH 08/18] writeback: trace dirty_ratelimit Wu Fengguang
2011-09-04 1:53 ` [PATCH 09/18] writeback: trace balance_dirty_pages Wu Fengguang
2011-09-04 1:53 ` [PATCH 10/18] writeback: dirty position control - bdi reserve area Wu Fengguang
2011-09-06 14:09 ` Peter Zijlstra
2011-09-07 12:31 ` Wu Fengguang
2011-09-12 10:19 ` Peter Zijlstra
2011-09-18 14:17 ` Wu Fengguang
2011-09-18 14:37 ` Wu Fengguang
2011-09-18 14:47 ` Wu Fengguang
2011-09-28 14:02 ` Wu Fengguang
2011-09-28 14:50 ` Peter Zijlstra
2011-09-29 3:32 ` Wu Fengguang
2011-09-29 8:49 ` Peter Zijlstra
2011-09-29 11:05 ` Wu Fengguang
2011-09-29 12:15 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 11/18] block: add bdi flag to indicate risk of io queue underrun Wu Fengguang
2011-09-06 14:22 ` Peter Zijlstra
2011-09-07 2:37 ` Wu Fengguang
2011-09-07 7:31 ` Peter Zijlstra
2011-09-04 1:53 ` [PATCH 12/18] writeback: balanced_rate cannot exceed write bandwidth Wu Fengguang
2011-09-04 1:53 ` [PATCH 13/18] writeback: limit max dirty pause time Wu Fengguang
2011-09-06 14:52 ` Peter Zijlstra
2011-09-07 2:35 ` Wu Fengguang
2011-09-12 10:22 ` Peter Zijlstra
2011-09-18 14:23 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 14/18] writeback: control " Wu Fengguang
2011-09-06 15:51 ` Peter Zijlstra
2011-09-07 2:02 ` Wu Fengguang
2011-09-12 10:28 ` Peter Zijlstra
2011-09-04 1:53 ` [PATCH 15/18] writeback: charge leaked page dirties to active tasks Wu Fengguang
2011-09-06 16:16 ` Peter Zijlstra
2011-09-07 9:06 ` Wu Fengguang
2011-09-07 0:17 ` Jan Kara
2011-09-07 9:37 ` Wu Fengguang
2011-09-04 1:53 ` [PATCH 16/18] writeback: fix dirtied pages accounting on sub-page writes Wu Fengguang
2011-09-04 1:53 ` [PATCH 17/18] writeback: fix dirtied pages accounting on redirty Wu Fengguang
2011-09-06 16:18 ` Peter Zijlstra
2011-09-07 0:22 ` Jan Kara
2011-09-07 1:18 ` Wu Fengguang
2011-09-07 6:56 ` Christoph Hellwig
2011-09-07 8:19 ` Peter Zijlstra [this message]
2011-09-07 16:42 ` Jan Kara
2011-09-07 16:46 ` Christoph Hellwig
2011-09-08 8:51 ` Steven Whitehouse
2011-09-04 1:53 ` [PATCH 18/18] btrfs: fix dirtied pages accounting on sub-page writes Wu Fengguang
2011-09-07 13:32 ` [PATCH 00/18] IO-less dirty throttling v11 Wu Fengguang
2011-09-07 19:14 ` Trond Myklebust
2011-09-28 14:58 ` Christoph Hellwig
2011-09-29 4:11 ` Wu Fengguang
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