From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MiFxd-000674-Vl for qemu-devel@nongnu.org; Mon, 31 Aug 2009 19:06:54 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MiFxZ-00063j-EK for qemu-devel@nongnu.org; Mon, 31 Aug 2009 19:06:53 -0400 Received: from [199.232.76.173] (port=55288 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MiFxZ-00063f-5J for qemu-devel@nongnu.org; Mon, 31 Aug 2009 19:06:49 -0400 Received: from verein.lst.de ([213.95.11.210]:40412) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_3DES_EDE_CBC_SHA1:24) (Exim 4.60) (envelope-from ) id 1MiFxY-0003dx-OV for qemu-devel@nongnu.org; Mon, 31 Aug 2009 19:06:49 -0400 Date: Tue, 1 Sep 2009 01:06:46 +0200 From: Christoph Hellwig Subject: Re: [Qemu-devel] [PATCH 1/4] block: add enable_write_cache flag Message-ID: <20090831230646.GA10649@lst.de> References: <20090831201627.GA4811@lst.de> <20090831201651.GA4874@lst.de> <20090831220950.GB24318@shareable.org> <20090831221622.GA8834@lst.de> <4A9C5463.4090904@codemonkey.ws> <20090831225925.GG24318@shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090831225925.GG24318@shareable.org> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jamie Lokier Cc: Christoph Hellwig , qemu-devel@nongnu.org On Mon, Aug 31, 2009 at 11:59:25PM +0100, Jamie Lokier wrote: > Anthony Liguori wrote: > > Can someone do some benchmarking with cache=writeback and fdatasync > > first and quantify what the real performance impact is? > > Unfortunately we can't yet quantify the impact on the hardware I care > about (ordinary consumer PCs with non-NCQ SATA disks), because Linux > hosts don't *yet* implement O_SYNC or fdatasync properly. They do if you use XFS.