From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [Qemu-devel] Re: [PATCH 0/3] Refactor AIO to allow multiple AIO implementations Date: Tue, 23 Sep 2008 09:47:17 -0500 Message-ID: <48D90175.1010009@us.ibm.com> References: <1222125454-21744-1-git-send-email-ryanh@us.ibm.com> <48D86361.4000405@us.ibm.com> <20080923144319.GM31395@us.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org To: Ryan Harper Return-path: Received: from e4.ny.us.ibm.com ([32.97.182.144]:44795 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751241AbYIWOtc (ORCPT ); Tue, 23 Sep 2008 10:49:32 -0400 Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e4.ny.us.ibm.com (8.13.8/8.13.8) with ESMTP id m8NEnVT4012671 for ; Tue, 23 Sep 2008 10:49:31 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id m8NEmEHL233630 for ; Tue, 23 Sep 2008 10:48:15 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m8NEmEek019256 for ; Tue, 23 Sep 2008 10:48:14 -0400 In-Reply-To: <20080923144319.GM31395@us.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: Ryan Harper wrote: > * Anthony Liguori [2008-09-22 22:44]: > >> Can you run the same performance tests with the following patches (using >> sync=on instead of cache=off)? >> >> You'll need my aio_init fix too. I suspect this will give equally good >> performance to your patch set. That's not saying your patch set isn't >> useful, but I would like to get performance to be better for the case >> that we're going through the page cache. >> > > I can run the test, but it is orthogonal to the patchset which is > focused on using O_DIRECT and linux-aio. > Yes, I'm trying to understand where the performance is coming from. The hunch is that supporting multiple simultaneous requests along is what did it. O_SYNC should give similar completion behavior to O_DIRECT. Regards, Anthony Liguori