From: Jens Axboe <jaxboe@fusionio.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: merging discard request in the block layer
Date: Wed, 23 Mar 2011 16:26:43 +0100 [thread overview]
Message-ID: <4D8A1133.20502@fusionio.com> (raw)
In-Reply-To: <20110323130137.GA10455@infradead.org>
On 2011-03-23 14:01, Christoph Hellwig wrote:
> On Tue, Mar 22, 2011 at 10:03:57PM +0100, Jens Axboe wrote:
>>> That would seem to indicate a bug in the merging logic instead.
>>
>> What kind of max discard size does you device have? If the max discard
>> size is smaller than the regular request size, this could help.
>
> It's a SCSI device, so the max discard size is a lot larger:
>
> # cat /sys/block/sda/queue/max_sectors_kb
> 512
> # cat /sys/block/sda/queue/max_hw_sectors_kb
> 32767
> # cat /sys/block/sda/queue/discard_max_bytes
> 4294966784
I'll try and throw a synthetic test at it that produces a slew of
discard merging and see what happens.
--
Jens Axboe
next prev parent reply other threads:[~2011-03-23 15:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-22 19:47 merging discard request in the block layer Christoph Hellwig
2011-03-22 19:54 ` Jens Axboe
2011-03-22 21:00 ` Christoph Hellwig
2011-03-22 21:03 ` Jens Axboe
2011-03-23 13:01 ` Christoph Hellwig
2011-03-23 15:26 ` Jens Axboe [this message]
2011-03-30 14:16 ` Christoph Hellwig
2011-05-03 18:05 ` Christoph Hellwig
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