From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49180) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WQyDd-0001pi-Or for qemu-devel@nongnu.org; Fri, 21 Mar 2014 08:06:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WQyDY-00050t-Sr for qemu-devel@nongnu.org; Fri, 21 Mar 2014 08:06:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60904) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WQyDY-000501-L9 for qemu-devel@nongnu.org; Fri, 21 Mar 2014 08:06:32 -0400 Message-ID: <532C2B38.7050708@redhat.com> Date: Fri, 21 Mar 2014 13:06:16 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1395402552-22366-1-git-send-email-pl@kamp.de> In-Reply-To: <1395402552-22366-1-git-send-email-pl@kamp.de> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCHv2] block: introduce BDRV_O_SEQUENTIAL List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven , qemu-devel@nongnu.org Cc: kwolf@redhat.com, shadowsor@gmail.com, famz@redhat.com, stefanha@redhat.com Il 21/03/2014 12:49, Peter Lieven ha scritto: > A 10G logical volume was created and filled with random data. > Then the logical volume was exported via qemu-img convert to an iscsi target. > Before the export was started all caches of the linux kernel where dropped. > > Old behavior: > - The convert process took 3m45s and the buffer cache grew up to 9.67 GB close > to the end of the conversion. After qemu-img terminated all the buffers were > freed by the kernel. > > New behavior with the -N switch: > - The convert process took 3m43s and the buffer cache grew up to 15.48 MB close > to the end with some small peaks up to 30 MB durine the conversion. > > Signed-off-by: Peter Lieven > --- > v1->v2: - added test example to commit msg > - added -N knob to qemu-img I'm sorry, I cannot find the original discussion. Why is the new knob needed? Paolo