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From: Nigel Cunningham <nigel@tuxonice.net>
To: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	tj@kernel.org, chris.mason@oracle.com, swhiteho@redhat.com,
	konishi.ryusuke@lab.ntt.co.jp, tytso@mit.edu, jack@suse.cz,
	hirofumi@mail.parknet.co.jp, mfasheh@suse.com,
	joel.becker@oracle.com, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 12/15] swap: do not send discards as barriers
Date: Sun, 22 Aug 2010 22:20:16 +1000	[thread overview]
Message-ID: <4C711600.9000407@tuxonice.net> (raw)
In-Reply-To: <alpine.DEB.1.00.1008182035520.27248@tigran.mtv.corp.google.com>

Hi.

On 19/08/10 13:47, Hugh Dickins wrote:
> On Wed, 18 Aug 2010, Christoph Hellwig wrote:
>
>> The swap code already uses synchronous discards, no need to add I/O barriers.
>>
>> Signed-off-by: Christoph Hellwig<hch@lst.de>
>
> Acked-by: Hugh Dickins<hughd@google.com>
>
> (though if you happened to respin, I'd be be glad for those newlines
> between GFP_KERNEL, BLKDEV_IFL_WAIT to go away now)
>
> This patch could go in any time now: I may want to push it in and
> get it to 35-stable, because it certainly helps against the swap
> discard regression that Nigel reported (though I've not yet seen
> his numbers with this).  However, I don't think it eliminates the
> regression, so I've more testing and experimenting to do before
> deciding about it - the right answer may just be to disable swap
> discard, as you asked for long ago.

That's correct. The patch reduces the pause from minutes to a matter of 
seconds (with 4GB of swap), but it is still there (there was previously 
no discernable delay).

Tested-by: Nigel Cunningham <nigel@tuxonice.net>

Regards,

Nigel

  parent reply	other threads:[~2010-08-22 12:20 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-18  9:29 [PATCH 00/15] replace barriers with explicit flush / FUA usage Christoph Hellwig
2010-08-18  9:29 ` [PATCH 01/15] kill BH_Ordered flag Christoph Hellwig
2010-08-18  9:29 ` [PATCH 02/15] pass gfp_mask and flags to sb_issue_discard Christoph Hellwig
2010-08-20  1:23   ` Mike Snitzer
2010-08-18  9:29 ` [PATCH 03/15] xfs: replace barriers with explicit flush / FUA usage Christoph Hellwig
2010-08-18 23:47   ` Dave Chinner
2010-08-18  9:29 ` [PATCH 04/15] btrfs: " Christoph Hellwig
2010-08-18 12:06   ` Chris Mason
2010-08-18  9:29 ` [PATCH 05/15] gfs2: " Christoph Hellwig
2010-08-18 10:08   ` Steven Whitehouse
2010-08-18 13:37   ` Bob Peterson
2010-08-18  9:29 ` [PATCH 06/15] reiserfs: " Christoph Hellwig
2010-08-18 13:16   ` Jan Kara
2010-08-18 13:21     ` Chris Mason
2010-08-18  9:29 ` [PATCH 07/15] nilfs2: " Christoph Hellwig
2010-08-18 13:31   ` Ryusuke Konishi
2010-08-18 13:41     ` Christoph Hellwig
2010-08-18  9:29 ` [PATCH 08/15] jbd: " Christoph Hellwig
2010-08-18 13:07   ` Jan Kara
2010-08-18  9:29 ` [PATCH 09/15] jbd2: " Christoph Hellwig
2010-08-18 14:03   ` Jan Kara
2010-08-18 14:09     ` Christoph Hellwig
2010-08-18  9:29 ` [PATCH 10/15] ext4: do not send discards as barriers Christoph Hellwig
2010-08-18 13:28   ` Jan Kara
2010-08-18  9:29 ` [PATCH 11/15] fat: " Christoph Hellwig
2010-08-18  9:29 ` [PATCH 12/15] swap: " Christoph Hellwig
2010-08-19  3:47   ` Hugh Dickins
2010-08-19  4:08     ` Nigel Cunningham
2010-08-19  9:02     ` Christoph Hellwig
2010-08-19 11:35       ` Chris Mason
2010-08-22 12:20     ` Nigel Cunningham [this message]
2010-08-18  9:29 ` [PATCH 13/15] remove the WRITE_BARRIER flag Christoph Hellwig
2010-08-18  9:29 ` [PATCH 14/15] remove the BLKDEV_IFL_BARRIER flag Christoph Hellwig
2010-08-20  1:26   ` Mike Snitzer
2010-08-18  9:29 ` [PATCH 15/15] remove the BH_Eopnotsupp flag Christoph Hellwig
2010-08-18 10:35 ` [PATCH 00/15] replace barriers with explicit flush / FUA usage Joel Becker
2010-08-18 10:53   ` Christoph Hellwig
2010-08-20  6:50     ` Tao Ma
2010-08-18 15:11 ` Ted Ts'o
2010-08-18 16:46   ` Christoph Hellwig
2010-08-20  4:00 ` Tao Ma

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