From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [Qemu-devel] [RFC] Replace posix-aio with custom thread pool Date: Tue, 09 Dec 2008 19:16:51 +0200 Message-ID: <493EA803.9060703@redhat.com> References: <1228512061-25398-1-git-send-email-aliguori@us.ibm.com> <493E941D.4000608@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Anthony Liguori , kvm-devel To: qemu-devel@nongnu.org Return-path: Received: from mx2.redhat.com ([66.187.237.31]:39233 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754435AbYLIRQ5 (ORCPT ); Tue, 9 Dec 2008 12:16:57 -0500 In-Reply-To: <493E941D.4000608@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Gerd Hoffmann wrote: > Well, I see a massive slowdown when switching from sync to aio in the > xen backend code. I think the reason is that due to the lack of a > vectored interface (and thus /me submitting separate aio requests for > each iovec element) stuff gets parallelized *way* too much and disk seek > times are killing me. > Try switching to the deadline io scheduler. cfq has a known issue with this. -- error compiling committee.c: too many arguments to function