From: Kevin Wolf <kwolf@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org,
stefanha@redhat.com, famz@redhat.com, mreitz@redhat.com,
jcody@redhat.com, eblake@redhat.com, pbonzini@redhat.com,
"Denis V. Lunev" <den@openvz.org>
Subject: Re: [Qemu-devel] [PATCH v2] mirror: double performance of the bulk stage if the disc is full
Date: Wed, 3 Aug 2016 12:52:33 +0200 [thread overview]
Message-ID: <20160803105233.GB4629@noname.redhat.com> (raw)
In-Reply-To: <1468516741-82174-1-git-send-email-vsementsov@virtuozzo.com>
Am 14.07.2016 um 19:19 hat Vladimir Sementsov-Ogievskiy geschrieben:
> Mirror can do up to 16 in-flight requests, but actually on full copy
> (the whole source disk is non-zero) in-flight is always 1. This happens
> as the request is not limited in size: the data occupies maximum available
> capacity of s->buf.
>
> The patch limits the size of the request to some artificial constant
> (1 Mb here), which is not that big or small. This effectively enables
> back parallelism in mirror code as it was designed.
>
> The result is important: the time to migrate 10 Gb disk is reduced from
> ~350 sec to 170 sec.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
This broke qemu-iotests 109 for raw. Can you please check whether the
output changes are expected, and send a fix either for the code or for
the test case?
Kevin
next prev parent reply other threads:[~2016-08-03 10:52 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-14 17:19 [Qemu-devel] [PATCH v2] mirror: double performance of the bulk stage if the disc is full Vladimir Sementsov-Ogievskiy
2016-07-18 15:36 ` Denis V. Lunev
2016-07-20 17:36 ` Denis V. Lunev
2016-07-20 19:08 ` Paolo Bonzini
2016-07-20 20:30 ` Denis V. Lunev
2016-07-22 16:41 ` Max Reitz
2016-07-26 2:47 ` Jeff Cody
2016-07-26 2:48 ` Jeff Cody
2016-08-03 10:52 ` Kevin Wolf [this message]
2016-08-03 12:20 ` Vladimir Sementsov-Ogievskiy
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