From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: sync guest calls made async on host - SQLite performance Date: Fri, 25 Sep 2009 10:22:45 +0300 Message-ID: <4ABC6FC5.6080007@redhat.com> References: <4ABA45BE.1080008@gmail.com> <4ABB5BAD.3000007@redhat.com> <4ABB6E07.60909@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Matthew Tippett Return-path: Received: from mx1.redhat.com ([209.132.183.28]:30075 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751516AbZIYHWs (ORCPT ); Fri, 25 Sep 2009 03:22:48 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 09/24/2009 10:49 PM, Matthew Tippett wrote: > The test itself is a simple usage of SQLite. It is stock KVM as > available in 2.6.31 on Ubuntu Karmic. So it would be the environment, > not the test. > > So assuming that KVM upstream works as expected that would leave > either 2.6.31 having an issue, or Ubuntu having an issue. > > Care to make an assertion on the KVM in 2.6.31? Leaving only Ubuntu's > installation. > kvm has nothing to do with it, it's purely qemu. For a long time qemu has defaulted to write-through cacheing. This can be overridden and maybe that's what Ubuntu or Phoronix do. > Can some KVM developers attempt to confirm that a 'correctly' > configured KVM will not demonstrate this behaviour? > http://www.phoronix-test-suite.com/ (or is already available in newer > distributions of Fedora, openSUSE and Ubuntu. > A correctly configured kvm will not demonstrate this behaviour. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.