From: Shaohua Li <shli@kernel.org>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Vivek Goyal <vgoyal@redhat.com>,
linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
neilb@suse.de, axboe@kernel.dk
Subject: Re: [patch v2 2/6] blk: dont allow discard request merge temporarily
Date: Thu, 22 Mar 2012 10:33:50 +0800 [thread overview]
Message-ID: <CANejiEVqPVJ_Rcx60287ypgJg0CBTqX+ozQR-y3jK=UY+SosXg@mail.gmail.com> (raw)
In-Reply-To: <yq1d385wf75.fsf@sermon.lab.mkp.net>
2012/3/22 Martin K. Petersen <martin.petersen@oracle.com>:
>>>>>> "Shaohua" == Shaohua Li <shli@kernel.org> writes:
>
> Shaohua> Enabling discard merge is required for device with slow discard
> Shaohua> (and very helpful for raid),
>
> Before RAID support there really wasn't much point. That's one of the
> reasons the current discard merge code has survived despite being
> completely broken.
Exactly.
> As for how I'd like to handle contiguous discard merges going forward
> here's a proof of concept. It's on top of my write same tree so you may
> have to noodle a bit.
>
> It is crucially important that we never merge a command that can't be
> processed by the device. So I'd like to do something like this:
This is great to consolidate the check with this patch. But looks this
isn't enough. As far as I know the current discard merge is broken
because blk_update_request() can't handle such request because
we override the first BIO to add payload. I had a quick hack and post
out yesterday. It works in my SATA ssd, but I really didn't know if there
is something missing in SCSI side, can you share anything here?
Thanks,
Shaohua
next prev parent reply other threads:[~2012-03-22 2:33 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-16 7:32 [patch v2 0/6] Add TRIM support for raid linear/0/1/10 Shaohua Li
2012-03-16 7:32 ` [patch v2 1/6] block: makes bio_split support bio without data Shaohua Li
2012-03-16 7:32 ` [patch v2 2/6] blk: dont allow discard request merge temporarily Shaohua Li
2012-03-20 16:21 ` Vivek Goyal
2012-03-21 1:22 ` Shaohua Li
2012-03-21 12:14 ` [patch 1/2]block: handle merged discard request Shaohua Li
2012-03-22 2:32 ` Martin K. Petersen
2012-03-22 2:39 ` Shaohua Li
2012-03-22 2:53 ` Martin K. Petersen
2012-06-20 8:57 ` Christoph Hellwig
2012-06-22 3:46 ` Martin K. Petersen
2012-08-03 2:10 ` Shaohua Li
2012-08-18 3:06 ` Mike Snitzer
2012-08-18 3:47 ` Martin K. Petersen
2012-08-20 13:57 ` Mike Snitzer
2012-08-20 13:58 ` Christoph Hellwig
2012-08-20 14:12 ` Mike Snitzer
2012-08-20 14:15 ` Christoph Hellwig
2012-03-22 2:18 ` [patch v2 2/6] blk: dont allow discard request merge temporarily Martin K. Petersen
2012-03-22 2:33 ` Shaohua Li [this message]
2012-03-22 6:28 ` Christoph Hellwig
2012-03-16 7:32 ` [patch v2 3/6] md: linear supports TRIM Shaohua Li
2012-03-16 7:32 ` [patch v2 4/6] md: raid 0 " Shaohua Li
2012-03-16 7:32 ` [patch v2 5/6] md: raid 1 " Shaohua Li
2012-03-16 7:32 ` [patch v2 6/6] md: raid 10 " Shaohua Li
2012-03-19 19:38 ` [patch v2 0/6] Add TRIM support for raid linear/0/1/10 Holger Kiehl
2012-03-20 1:27 ` Shaohua Li
2012-03-20 9:50 ` Holger Kiehl
2012-03-20 12:09 ` Shaohua Li
2012-03-21 2:08 ` Shaohua Li
2012-03-21 2:24 ` Roberto Spadim
2012-03-21 2:29 ` Mathias Burén
2012-03-21 2:29 ` Mathias Burén
2012-05-08 9:59 ` Patelczyk, Maciej
2012-05-09 2:27 ` Shaohua Li
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