From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: sync guest calls made async on host - SQLite performance Date: Thu, 15 Oct 2009 14:17:02 +0200 Message-ID: <20091015121702.GA3780@lst.de> References: <4ACF89CB.5020406@gmail.com> <4AD1A27A.4060307@redhat.com> <20091013223714.GB16152@lst.de> <4AD5B00D.102@redhat.com> <20091014134122.GA14235@lst.de> <4AD602C8.4090603@redhat.com> <20091014170215.GA22621@lst.de> <4AD6569F.80803@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoph Hellwig , Avi Kivity , Matthew Tippett , Dustin Kirkland , RW , kvm@vger.kernel.org To: Anthony Liguori Return-path: Received: from verein.lst.de ([213.95.11.210]:59416 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752202AbZJOMRw (ORCPT ); Thu, 15 Oct 2009 08:17:52 -0400 Content-Disposition: inline In-Reply-To: <4AD6569F.80803@codemonkey.ws> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Oct 14, 2009 at 05:54:23PM -0500, Anthony Liguori wrote: > >Historically it didn't and the only safe way to use virtio was in > >cache=writethrough mode. > > Which should be the default on Ubuntu's kvm that this report is > concerned with so I'm a bit confused. So can we please get the detailed setup where this happens, that is: filesystem used in the guest any volume manager / software raid used in the guest kernel version in the guest image format used qemu command line including caching mode, using ide/scsi/virtio, etc qemu/kvm version filesystem used in the host any volume manager / software raid used in the host kernel version in the host > Avi's patch is a performance optimization, not a correctness issue? It could actually minimally degrade performace. For the existing filesystems as upper layer it doesn not improve correctness either.