From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754682AbYKJKqu (ORCPT ); Mon, 10 Nov 2008 05:46:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753530AbYKJKql (ORCPT ); Mon, 10 Nov 2008 05:46:41 -0500 Received: from pasmtpa.tele.dk ([80.160.77.114]:60671 "EHLO pasmtpA.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750815AbYKJKqk (ORCPT ); Mon, 10 Nov 2008 05:46:40 -0500 Date: Mon, 10 Nov 2008 11:44:24 +0100 From: Jens Axboe To: "Vitaly V. Bursov" Cc: linux-kernel@vger.kernel.org Subject: Re: Slow file transfer speeds with CFQ IO scheduler in some cases Message-ID: <20081110104423.GA26778@kernel.dk> References: <4917263D.2090904@telenet.dn.ua> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4917263D.2090904@telenet.dn.ua> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Nov 09 2008, Vitaly V. Bursov wrote: > Hello, > > I'm building small server system with openvz kernel and have ran into > some IO performance problems. Reading a single file via NFS delivers > around 9 MB/s over gigabit network, but while reading, say, 2 different > or same file 2 times at the same time I get >60MB/s. > > Changing IO scheduler to deadline or anticipatory fixes problem. > > Tested kernels: > OpenVZ RHEL5 028stab059.3 (9 MB/s with HZ=100, 20MB/s with HZ=1000 > fast local reads) > Vanilla 2.6.27.5 (40 MB/s with HZ=100, slow local reads) > > Vanilla performs better in worst case but I believe 40 is still low > concerning test results below. Can you check with this patch applied? http://bugzilla.kernel.org/attachment.cgi?id=18473&action=view -- Jens Axboe