From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1JmsRI-0000hv-Pi for qemu-devel@nongnu.org; Fri, 18 Apr 2008 11:23:48 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1JmsRG-0000hT-B3 for qemu-devel@nongnu.org; Fri, 18 Apr 2008 11:23:47 -0400 Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1JmsRG-0000hQ-3l for qemu-devel@nongnu.org; Fri, 18 Apr 2008 11:23:46 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1JmsRG-0008EF-3h for qemu-devel@nongnu.org; Fri, 18 Apr 2008 11:23:46 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e31.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id m3IFNcrj015938 for ; Fri, 18 Apr 2008 11:23:38 -0400 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m3IFNXtn155532 for ; Fri, 18 Apr 2008 09:23:37 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m3IFNWsx018139 for ; Fri, 18 Apr 2008 09:23:33 -0600 Message-ID: <4808BCF3.3060200@us.ibm.com> Date: Fri, 18 Apr 2008 10:23:31 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [kvm-devel] [PATCH 1/3] Refactor AIO interface to allow other AIO implementations References: <1208460412-27567-1-git-send-email-aliguori@us.ibm.com> <20080417193807.GB11916@redhat.com> <4807A7EC.6040408@us.ibm.com> <20080417200024.GC11916@redhat.com> <20080418124319.GC25089@shareable.org> In-Reply-To: <20080418124319.GC25089@shareable.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed 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: "Daniel P. Berrange" , qemu-devel@nongnu.org, Anthony Liguori , kvm-devel@lists.sourceforge.net, Marcelo Tosatti Jamie Lokier wrote: >> I've basically got a choice of making libvirt always ad '-aio linux' >> or never add it at all. My inclination is to the latter since it is >> compatible with existing QEMU which has no -aio option. Presumably >> '-aio linux' is intended to provide some performance benefit so it'd >> be nice to use it. If we can't express some criteria under which it >> should be turned on, I can't enable it; where as if you can express >> some criteria, then QEMU should apply them automatically. >> > > I'm of the view that '-aio auto' would be a really good option - and > when it's proven itself, it should be the default. It could work on > all QEMU hosts: it would pick synchronous IO when there is nothing else. > Right now, not specifying the -aio option is equivalent to your proposed -aio auto. I guess I should include an info aio to let the user know what type of aio they are using. We can add selection criteria later but semantically, not specifying an explicit -aio option allows QEMU to choose whichever one it thinks is best. Regards, Anthony Liguori