From: Jens Axboe <axboe@fb.com>
To: Ming Lei <ming.lei@canonical.com>, linux-kernel@vger.kernel.org
Cc: linux-block@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
Dexuan Cui <decui@microsoft.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Keith Busch <keith.busch@intel.com>,
Hannes Reinecke <hare@suse.de>,
Mike Christie <mchristi@redhat.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Toshi Kani <toshi.kani@hpe.com>,
Dan Williams <dan.j.williams@intel.com>,
Damien Le Moal <damien.lemoal@hgst.com>
Subject: Re: [PATCH] block: loose check on sg gap
Date: Sat, 17 Dec 2016 09:49:35 -0700 [thread overview]
Message-ID: <f470bfb2-9a82-dcc8-b018-5697d4694a1b@fb.com> (raw)
In-Reply-To: <1481971751-4016-1-git-send-email-ming.lei@canonical.com>
On 12/17/2016 03:49 AM, Ming Lei wrote:
> If the last bvec of the 1st bio and the 1st bvec of the next
> bio are contineous physically, and the latter can be merged
> to last segment of the 1st bio, we should think they don't
> violate sg gap(or virt boundary) limit.
>
> Both Vitaly and Dexuan reported lots of unmergeable small bios
> are observed when running mkfs on Hyper-V virtual storage, and
> performance becomes quite low, so this patch is figured out for
> fixing the performance issue.
>
> The same issue should exist on NVMe too sine it sets virt boundary too.
It looks pretty reasonable to me. I'll queue it up for some testing,
changes like this always make me a little nervous.
--
Jens Axboe
WARNING: multiple messages have this Message-ID (diff)
From: Jens Axboe <axboe@fb.com>
To: Ming Lei <ming.lei@canonical.com>, <linux-kernel@vger.kernel.org>
Cc: <linux-block@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
Dexuan Cui <decui@microsoft.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Keith Busch <keith.busch@intel.com>,
Hannes Reinecke <hare@suse.de>,
"Mike Christie" <mchristi@redhat.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Toshi Kani <toshi.kani@hpe.com>,
Dan Williams <dan.j.williams@intel.com>,
Damien Le Moal <damien.lemoal@hgst.com>
Subject: Re: [PATCH] block: loose check on sg gap
Date: Sat, 17 Dec 2016 09:49:35 -0700 [thread overview]
Message-ID: <f470bfb2-9a82-dcc8-b018-5697d4694a1b@fb.com> (raw)
In-Reply-To: <1481971751-4016-1-git-send-email-ming.lei@canonical.com>
On 12/17/2016 03:49 AM, Ming Lei wrote:
> If the last bvec of the 1st bio and the 1st bvec of the next
> bio are contineous physically, and the latter can be merged
> to last segment of the 1st bio, we should think they don't
> violate sg gap(or virt boundary) limit.
>
> Both Vitaly and Dexuan reported lots of unmergeable small bios
> are observed when running mkfs on Hyper-V virtual storage, and
> performance becomes quite low, so this patch is figured out for
> fixing the performance issue.
>
> The same issue should exist on NVMe too sine it sets virt boundary too.
It looks pretty reasonable to me. I'll queue it up for some testing,
changes like this always make me a little nervous.
--
Jens Axboe
next prev parent reply other threads:[~2016-12-17 16:49 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-17 10:49 [PATCH] block: loose check on sg gap Ming Lei
2016-12-17 16:49 ` Jens Axboe [this message]
2016-12-17 16:49 ` Jens Axboe
2016-12-20 2:07 ` Ming Lei
2016-12-20 2:31 ` Jens Axboe
2016-12-20 3:41 ` Dexuan Cui
2017-01-11 5:10 ` Dexuan Cui
2017-01-12 2:54 ` Ming Lei
2017-01-12 3:14 ` Dexuan Cui
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