From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38491) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WSjxR-0005pA-F6 for qemu-devel@nongnu.org; Wed, 26 Mar 2014 05:17:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WSjxM-0007Id-Fa for qemu-devel@nongnu.org; Wed, 26 Mar 2014 05:17:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57131) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WSjxM-0007IH-8c for qemu-devel@nongnu.org; Wed, 26 Mar 2014 05:17:08 -0400 From: Markus Armbruster References: <1395412589-30601-1-git-send-email-pl@kamp.de> Date: Wed, 26 Mar 2014 10:16:58 +0100 In-Reply-To: <1395412589-30601-1-git-send-email-pl@kamp.de> (Peter Lieven's message of "Fri, 21 Mar 2014 15:36:29 +0100") Message-ID: <87fvm5720l.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [RFC PATCHv2] block: optimize zero writes with bdrv_write_zeroes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: kwolf@redhat.com, famz@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com, stefanha@redhat.com, pbonzini@redhat.com Peter Lieven writes: > this patch tries to optimize zero write requests > by automatically using bdrv_write_zeroes if it is > supported by the format. > > this should significantly speed up file system initialization and > should speed zero write test used to test backend storage performance. > > the difference can simply be tested by e.g. > > dd if=/dev/zero of=/dev/vdX bs=1M Got actual numbers? Preferably for some operation that matters to users. [...]