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: Thu, 24 Sep 2009 16:03:03 +0300 Message-ID: <4ABB6E07.60909@redhat.com> References: <4ABA45BE.1080008@gmail.com> <4ABB5BAD.3000007@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]:4518 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751206AbZIXNDE (ORCPT ); Thu, 24 Sep 2009 09:03:04 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 09/24/2009 03:31 PM, Matthew Tippett wrote: > Thanks Avi, > > I am still trying to reconcile the your statement with the potential > data risks and the numbers observed. > > My read of your response is that the guest sees a consistent view - > the data is commited to the virtual disk device. Does a synchronous > write within the guest trigger a synchronous write of the virtual > device within the host? > Yes. > I don't think offering SQLite users a 10 fold increase in performance > with no data integrity risks just by using KVM is a sane proposition. > It isn't, my guess is that the test setup is broken somehow. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.