From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1KpStJ-0001Ol-FB for qemu-devel@nongnu.org; Mon, 13 Oct 2008 15:15:41 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1KpStF-0001OZ-0f for qemu-devel@nongnu.org; Mon, 13 Oct 2008 15:15:40 -0400 Received: from [199.232.76.173] (port=58929 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1KpStE-0001OW-Rk for qemu-devel@nongnu.org; Mon, 13 Oct 2008 15:15:36 -0400 Received: from e8.ny.us.ibm.com ([32.97.182.138]:41944) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1KpStE-0004Pa-Ar for qemu-devel@nongnu.org; Mon, 13 Oct 2008 15:15:36 -0400 Received: from d01relay02.pok.ibm.com (d01relay02.pok.ibm.com [9.56.227.234]) by e8.ny.us.ibm.com (8.13.1/8.13.1) with ESMTP id m9DJCYEM017233 for ; Mon, 13 Oct 2008 15:12:34 -0400 Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by d01relay02.pok.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id m9DJFUs2287754 for ; Mon, 13 Oct 2008 15:15:30 -0400 Received: from d01av03.pok.ibm.com (loopback [127.0.0.1]) by d01av03.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m9DJFTJ7008593 for ; Mon, 13 Oct 2008 15:15:29 -0400 Date: Mon, 13 Oct 2008 14:15:28 -0500 From: Ryan Harper Subject: Re: [Qemu-devel] Re: [RFC] Disk integrity in QEMU Message-ID: <20081013191528.GI21410@us.ibm.com> References: <48EE38B9.2050106@codemonkey.ws> <20081013170610.GF21410@us.ibm.com> <48F39AE3.4060000@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48F39AE3.4060000@redhat.com> Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Mark Wagner Cc: Chris Wright , Mark McLoughlin , kvm-devel , Laurent Vivier , qemu-devel@nongnu.org, Ryan Harper * Mark Wagner [2008-10-13 14:06]: > Ryan Harper wrote: > > Can you please post the details of the guest and host configurations. http://lists.gnu.org/archive/html/qemu-devel/2008-09/msg01115.html > From seeing kvm write data that is greater than that of bare metal, > I would think that your test dataset is too small and not > exceeding that of the host cache size. The size was chosen so it would fit in to demonstrate the crazy #'s seen on cached writes without O_DSYNC. > > Our previous testing has shown that once you exceed the host cache > and cause the cache to flush, performance will drop to a point lower > than if you didn't use the cache in the first place. > > Can you repeat the tests using a data set that is 2X the size of your > hosts memory and post the results for the community to see? Yeah, I can generate those numbers as well. Seeing your note about tons of ESA and storage, feel free to generate your own #'s and post them for the community as well; the more the merrier. -- Ryan Harper Software Engineer; Linux Technology Center IBM Corp., Austin, Tx (512) 838-9253 T/L: 678-9253 ryanh@us.ibm.com