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From: Jens Axboe <axboe@kernel.dk>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-xfs@vger.kernel.org, linux-block@vger.kernel.org
Subject: Re: [PATCHSET 0/2] sync discard
Date: Wed, 2 May 2018 08:19:43 -0600	[thread overview]
Message-ID: <b219c171-1b28-d7ea-f5b9-c352da64cafb@kernel.dk> (raw)
In-Reply-To: <20180502124508.GD22857@lst.de>

On 5/2/18 6:45 AM, Christoph Hellwig wrote:
> On Mon, Apr 30, 2018 at 09:32:50AM -0600, Jens Axboe wrote:
>> We recently had a pretty severe perf regression with the XFS async
>> discard. This small series add a SYNC issue discard flag, and also
>> limits the chain size for sync discards. Patch 2 adds support for
>> reverting XFS back to doign sync discards.
> 
> Please explain the hardware and workload that you see this with.
> Also given that it is a hardware limitation a quirk limiting the
> size of discard requests and/or number of outstanding discards
> would be more useful than falling back to a broken mode of issueing
> block commands.

Honestly, from what I've seen in production, I can whitelist one
device and that one is no longer being produced. The rest is crap
in terms of latency impacting trim. A quirk or whitelist/blacklist
isn't going to be of any help.

-- 
Jens Axboe

      reply	other threads:[~2018-05-02 14:19 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30 15:32 [PATCHSET 0/2] sync discard Jens Axboe
2018-04-30 15:32 ` [PATCH 1/2] block: add BLKDEV_DISCARD_SYNC flag Jens Axboe
2018-04-30 15:32 ` [PATCH 2/2] xfs: add 'discard_sync' mount flag Jens Axboe
2018-04-30 17:19   ` Brian Foster
2018-04-30 18:07     ` Jens Axboe
2018-04-30 18:25       ` Luis R. Rodriguez
2018-04-30 18:31         ` Jens Axboe
2018-04-30 19:19         ` Eric Sandeen
2018-04-30 19:21           ` Jens Axboe
2018-04-30 19:57             ` Eric Sandeen
2018-04-30 19:58               ` Jens Axboe
2018-04-30 22:59                 ` Eric Sandeen
2018-04-30 23:02                   ` Jens Axboe
2018-04-30 19:18       ` Brian Foster
2018-04-30 21:31   ` Dave Chinner
2018-04-30 21:42     ` Jens Axboe
2018-04-30 22:28       ` Dave Chinner
2018-04-30 22:40         ` Jens Axboe
2018-04-30 23:00           ` Jens Axboe
2018-04-30 23:23             ` Dave Chinner
2018-05-01 11:11               ` Brian Foster
2018-05-01 15:23               ` Jens Axboe
2018-05-02  2:54                 ` Martin K. Petersen
2018-05-02 14:20                   ` Jens Axboe
2018-04-30 23:01           ` Darrick J. Wong
2018-05-02 12:45 ` [PATCHSET 0/2] sync discard Christoph Hellwig
2018-05-02 14:19   ` Jens Axboe [this message]

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