From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1M1N4h-0006VR-Ry for qemu-devel@nongnu.org; Tue, 05 May 2009 12:00:55 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1M1N4d-0006RR-4X for qemu-devel@nongnu.org; Tue, 05 May 2009 12:00:55 -0400 Received: from [199.232.76.173] (port=51715 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1M1N4c-0006Qz-FE for qemu-devel@nongnu.org; Tue, 05 May 2009 12:00:50 -0400 Received: from mail2.shareable.org ([80.68.89.115]:54113) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1M1N4b-0004Gj-S8 for qemu-devel@nongnu.org; Tue, 05 May 2009 12:00:50 -0400 Date: Tue, 5 May 2009 17:00:47 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] barriers: block layer preparations Message-ID: <20090505160047.GE31100@shareable.org> References: <20090505120804.GA30651@lst.de> <20090505120817.GA30721@lst.de> <4A00446B.7070404@redhat.com> <20090505153809.GC31100@shareable.org> <4A00600D.30502@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A00600D.30502@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Christoph Hellwig , qemu-devel@nongnu.org Avi Kivity wrote: > Jamie Lokier wrote: > >Avi Kivity wrote: > > > >>An alternative approach is to add a new op, bdrv_aio_barrier(), > >>submitted immediately after the write. It's probably more complicated > >>overall. > >> > > > >Is it ok to submit a zero-length bdrv_aio_writev(), when you need a > >barrier without data? > > > > We could make it so. But my point was to make barriers and writes > orthogonal. Yes, and my point is that you _must_ make them orthogonal if zero-length write isn't permitted :-) -- Jamie