From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LA6Cg-0003SE-OO for qemu-devel@nongnu.org; Tue, 09 Dec 2008 12:16:58 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LA6Ce-0003RG-ST for qemu-devel@nongnu.org; Tue, 09 Dec 2008 12:16:58 -0500 Received: from [199.232.76.173] (port=50609 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LA6Ce-0003RC-PV for qemu-devel@nongnu.org; Tue, 09 Dec 2008 12:16:56 -0500 Received: from mx2.redhat.com ([66.187.237.31]:60319) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LA6Ce-0002sw-Fu for qemu-devel@nongnu.org; Tue, 09 Dec 2008 12:16:56 -0500 Message-ID: <493EA803.9060703@redhat.com> Date: Tue, 09 Dec 2008 19:16:51 +0200 From: Avi Kivity MIME-Version: 1.0 Subject: Re: [Qemu-devel] [RFC] Replace posix-aio with custom thread pool References: <1228512061-25398-1-git-send-email-aliguori@us.ibm.com> <493E941D.4000608@redhat.com> In-Reply-To: <493E941D.4000608@redhat.com> 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: qemu-devel@nongnu.org Cc: Anthony Liguori , kvm-devel 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