From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36805) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bUtn1-0001qB-Sy for qemu-devel@nongnu.org; Wed, 03 Aug 2016 06:52:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bUtn0-0007YM-VJ for qemu-devel@nongnu.org; Wed, 03 Aug 2016 06:52:43 -0400 Date: Wed, 3 Aug 2016 12:52:33 +0200 From: Kevin Wolf Message-ID: <20160803105233.GB4629@noname.redhat.com> References: <1468516741-82174-1-git-send-email-vsementsov@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1468516741-82174-1-git-send-email-vsementsov@virtuozzo.com> Subject: Re: [Qemu-devel] [PATCH v2] mirror: double performance of the bulk stage if the disc is full List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladimir Sementsov-Ogievskiy 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" 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 > Signed-off-by: Denis V. Lunev 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