Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262503AbVDYDLM (ORCPT ); Sun, 24 Apr 2005 23:11:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262501AbVDYDLL (ORCPT ); Sun, 24 Apr 2005 23:11:11 -0400 Received: from pat.uio.no ([129.240.130.16]:669 "EHLO pat.uio.no") by vger.kernel.org with ESMTP id S262503AbVDYDKO (ORCPT ); Sun, 24 Apr 2005 23:10:14 -0400 Subject: Re: bdflush/rpciod high CPU utilization, profile does not make sense From: Trond Myklebust To: Jakob Oestergaard Cc: Greg Banks , Linux Kernel Mailing List In-Reply-To: <20050424071523.GV17359@unthought.net> References: <20050411134703.GC13369@unthought.net> <1113230125.9962.7.camel@lade.trondhjem.org> <20050411144127.GE13369@unthought.net> <1113232905.9962.15.camel@lade.trondhjem.org> <20050411154211.GG13369@unthought.net> <1113267809.1956.242.camel@hole.melbourne.sgi.com> <20050412092843.GB17359@unthought.net> <20050419194515.GP17359@unthought.net> <1113950788.10685.9.camel@lade.trondhjem.org> <20050420135758.GS17359@unthought.net> <20050424071523.GV17359@unthought.net> Content-Type: text/plain Date: Sun, 24 Apr 2005 23:09:58 -0400 Message-Id: <1114398598.2874.32.camel@lade.trondhjem.org> Mime-Version: 1.0 X-Mailer: Evolution 2.0.4 Content-Transfer-Encoding: 7bit X-UiO-Spam-info: not spam, SpamAssassin (score=-3.594, required 12, autolearn=disabled, AWL 1.36, FORGED_RCVD_HELO 0.05, UIO_MAIL_IS_INTERNAL -5.00) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1916 Lines: 41 su den 24.04.2005 Klokka 09:15 (+0200) skreiv Jakob Oestergaard: > Performance on SMP NFS client: > File Block Num Seq Read Rand Read Seq Write Rand Write > Dir Size Size Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate (CPU%) > ------- ------ ------- --- ----------- ----------- ----------- ----------- > . 2000 4096 1 47.53 80.0% 5.013 2.79% 22.34 32.2% 6.510 14.9% > . 2000 4096 2 45.29 78.6% 8.068 5.44% 24.53 34.1% 7.042 14.9% > . 2000 4096 4 45.38 78.0% 11.02 7.95% 25.13 35.1% 7.525 18.0% > > Performance on UP NFS client: > File Block Num Seq Read Rand Read Seq Write Rand Write > Dir Size Size Thr Rate (CPU%) Rate (CPU%) Rate (CPU%) Rate (CPU%) > ------- ------ ------- --- ----------- ----------- ----------- ----------- > . 2000 4096 1 57.11 54.7% 69.60 24.9% 35.09 14.2% 6.656 19.1% > . 2000 4096 2 60.11 58.8% 70.99 30.8% 33.82 14.1% 7.283 25.1% > . 2000 4096 4 67.89 59.8% 42.10 19.1% 29.86 12.7% 7.850 26.4% > > So, by booting the NFS client in uniprocessor mode, I got a 50% write > performance boost, 20% read perforamance boost, and the tests use about > half the CPU time. > > Isn't this a little disturbing? :) Actually, the most telling difference here is with the random read rates which shows up to 1000% difference. I seriously doubt that has much to do with lock contention (given that the sequential reads show 20% as you said). Could you once again have a look at the retransmission rates (both UDP and TCP), comparing the SMP and UP cases? Cheers, Trond -- Trond Myklebust - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/