From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:47558) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UDDhu-0000Qp-1U for qemu-devel@nongnu.org; Wed, 06 Mar 2013 07:44:31 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UDDht-0003ps-0J for qemu-devel@nongnu.org; Wed, 06 Mar 2013 07:44:29 -0500 Received: from mail-wg0-f51.google.com ([74.125.82.51]:56585) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UDDhs-0003pn-Cd for qemu-devel@nongnu.org; Wed, 06 Mar 2013 07:44:28 -0500 Received: by mail-wg0-f51.google.com with SMTP id 8so7279863wgl.6 for ; Wed, 06 Mar 2013 04:44:27 -0800 (PST) Date: Wed, 6 Mar 2013 13:44:24 +0100 From: Stefan Hajnoczi Message-ID: <20130306124424.GE1954@stefanha-thinkpad.muc.redhat.com> References: <20130222095736.GA6107@stefanha-thinkpad.redhat.com> <24E144B8C0207547AD09C467A8259F7557A70A61@lisa.maurer-it.com> <20130225134551.GE3202@stefanha-thinkpad.redhat.com> <24E144B8C0207547AD09C467A8259F7557AE0931@lisa.maurer-it.com> <20130228144920.GD18389@stefanha-thinkpad.redhat.com> <24E144B8C0207547AD09C467A8259F7557B12DDC@lisa.maurer-it.com> <20130304125806.GA18476@stefanha-thinkpad.redhat.com> <24E144B8C0207547AD09C467A8259F7557B277AE@lisa.maurer-it.com> <20130304135537.GC3929@dhcp-200-207.str.redhat.com> <24E144B8C0207547AD09C467A8259F7557B278C1@lisa.maurer-it.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <24E144B8C0207547AD09C467A8259F7557B278C1@lisa.maurer-it.com> Subject: Re: [Qemu-devel] [PATCH v4 3/6] add backup related monitor commands List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Dietmar Maurer Cc: Kevin Wolf , "qemu-devel@nongnu.org" On Mon, Mar 04, 2013 at 02:33:16PM +0000, Dietmar Maurer wrote: > > > > Is it using 64 KB writes and have you tried 256 KB writes? > > > > > > I use a modified 'qemu-img convert' at 64KB block size (I need 64KB for > > backup). > > > > Maybe you'd better use a different output format that doesn't restrict you to > > 64k writes. > > The output format is not really the restriction. The problem is that an additional > IPC layer add overhead, an d I do not want that (because it is totally unnecessary). I missed the reason why you cannot increase the block size. At least increase the NBD write size - the VMA process can break up a large write however it likes. Do this and the overhead is divided by 4. Stefan