From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Shaohua Li <shli@fusionio.com>,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
neilb@suse.de, axboe@kernel.dk,
"Martin K. Petersen" <martin.petersen@oracle.com>
Subject: Re: [patch 6/7] blk: add plug for blkdev_issue_discard
Date: Tue, 13 Mar 2012 13:04:58 -0400 [thread overview]
Message-ID: <yq1vcm8a0ud.fsf@sermon.lab.mkp.net> (raw)
In-Reply-To: <20120313155120.GG29169@redhat.com> (Vivek Goyal's message of "Tue, 13 Mar 2012 11:51:20 -0400")
>>>>> "Vivek" == Vivek Goyal <vgoyal@redhat.com> writes:
Vivek> On Mon, Mar 12, 2012 at 11:04:18AM +0800, Shaohua Li wrote:
>> In raid 0 case, a big discard request is divided into several small
>> requests in chunk_size unit. Such requests can be merged in low layer
>> if we have correct plug added. This should improve the performance a
>> little bit.
Vivek> Martin posted a patch to remove the support for allowing merging
Vivek> of discard requests. But this seems to be a reasonable use case
Vivek> for allowing mering discard requests. CCing Martin.
Merging discard requests is hard given how we need to prepare the
command payload at the bottom of the stack. The current upstream merge
code pretends to be working but it actually doesn't. That's why I want
it dead and buried.
I have some changes pending (that I need for the REQ_COPY support) that
will make merging of non-rw requests easier to deal with. But that's a
kernel release cycle away...
--
Martin K. Petersen Oracle Linux Engineering
next prev parent reply other threads:[~2012-03-13 17:05 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-12 3:04 [patch 0/7] Add TRIM support for raid linear/0/1/10 Shaohua Li
2012-03-12 3:04 ` [patch 1/7] block: makes bio_split support bio without data Shaohua Li
2012-03-12 3:04 ` [patch 2/7] md: linear supports TRIM Shaohua Li
2012-03-12 3:04 ` [patch 3/7] md: raid 0 " Shaohua Li
2012-03-12 3:04 ` [patch 4/7] md: raid 1 " Shaohua Li
2012-03-12 3:04 ` [patch 5/7] md: raid 10 " Shaohua Li
2012-03-12 3:04 ` [patch 6/7] blk: add plug for blkdev_issue_discard Shaohua Li
2012-03-13 15:51 ` Vivek Goyal
2012-03-13 17:04 ` Martin K. Petersen [this message]
2012-03-13 17:14 ` Vivek Goyal
2012-03-13 17:19 ` Martin K. Petersen
2012-03-12 3:04 ` [patch 7/7] blk: use correct sectors limitation for discard request Shaohua Li
2012-03-13 16:00 ` Vivek Goyal
2012-03-12 3:18 ` [patch 0/7] Add TRIM support for raid linear/0/1/10 Roberto Spadim
2012-03-12 18:22 ` Holger Kiehl
[not found] ` <4F5EFEB6.4060402@kernel.org>
2012-03-13 12:22 ` Holger Kiehl
2012-03-13 14:15 ` Shaohua Li
2012-03-13 14:58 ` Roberto Spadim
2012-03-13 15:44 ` Holger Kiehl
2012-03-14 1:30 ` Shaohua Li
2012-03-14 10:25 ` Holger Kiehl
2012-03-14 11:14 ` Shaohua Li
2012-03-14 11:32 ` Shaohua Li
2012-03-14 21:01 ` Holger Kiehl
2012-03-14 21:13 ` Holger Kiehl
2012-03-15 2:39 ` Shaohua Li
2012-03-15 9:08 ` Holger Kiehl
2012-03-16 2:19 ` Shaohua Li
[not found] ` <4F5EA8E9.5010502@fusionio.com>
2012-03-14 2:25 ` NeilBrown
2012-03-14 2:24 ` NeilBrown
2012-03-14 2:47 ` Shaohua Li
2012-03-17 18:14 ` Mark Lord
2012-03-18 2:03 ` Shaohua Li
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