From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Kpn5n-0002WK-Dk for qemu-devel@nongnu.org; Tue, 14 Oct 2008 12:49:55 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Kpn5l-0002VF-Tb for qemu-devel@nongnu.org; Tue, 14 Oct 2008 12:49:55 -0400 Received: from [199.232.76.173] (port=40456 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Kpn5l-0002Uz-Oc for qemu-devel@nongnu.org; Tue, 14 Oct 2008 12:49:53 -0400 Received: from mx2.redhat.com ([66.187.237.31]:33985) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Kpn5l-0002fX-DT for qemu-devel@nongnu.org; Tue, 14 Oct 2008 12:49:53 -0400 Message-ID: <48F4CD82.5040700@redhat.com> Date: Tue, 14 Oct 2008 18:49:06 +0200 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [RFC] Disk integrity in QEMU References: <48EE38B9.2050106@codemonkey.ws> <20081013170610.GF21410@us.ibm.com> <48F39AE3.4060000@redhat.com> <20081013191528.GI21410@us.ibm.com> In-Reply-To: <20081013191528.GI21410@us.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Chris Wright , Mark McLoughlin , kvm-devel , Laurent Vivier , Ryan Harper , Mark Wagner Ryan Harper wrote: >> 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. > > A disk that is smaller than host memory is hardly interesting. Give the memory to the guest and performance will jump to memory speed rather than disk speed. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.