From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:56309) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QCWa0-0000CL-L5 for qemu-devel@nongnu.org; Wed, 20 Apr 2011 08:32:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QCWZz-00041Y-LM for qemu-devel@nongnu.org; Wed, 20 Apr 2011 08:32:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30177) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QCWZz-00041I-D9 for qemu-devel@nongnu.org; Wed, 20 Apr 2011 08:32:23 -0400 Message-ID: <4DAED2E9.3030708@redhat.com> Date: Wed, 20 Apr 2011 14:34:49 +0200 From: Kevin Wolf MIME-Version: 1.0 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2] Improve accuracy of block migration bandwidth calculation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avishay Traeger Cc: qemu-devel@nongnu.org, Liran Schour , Michael Roth Am 03.04.2011 10:31, schrieb Avishay Traeger: > > Revised patch for improving the accuracy of the block migration bandwidth > calculation. Thanks a lot to Michael Roth for the input. > > For those that missed the original patch, here is the description: > block_mig_state.total_time is currently the sum of the read request > latencies. This is not very accurate because block migration uses aio and > so several requests can be submitted at once. Bandwidth should be computed > with wall-clock time, not by adding the latencies. In this case, > "total_time" has a higher value than it should, and so the computed > bandwidth is lower than it is in reality. This means that migration can > take longer than it needs to. > However, we don't want to use pure wall-clock time here. We are computing > bandwidth in the asynchronous phase, where the migration repeatedly wakes > up and sends some aio requests. The computed bandwidth will be used for > synchronous transfer. > > > Avishay > > > Signed-off-by: Avishay Traeger Thanks. Fixed line wraps and coding style and applied to the block branch. Please take care to avoid patch corruption next time - usually such patches are not fixed manually, but rejected. Kevin