Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757650Ab0HDLYc (ORCPT ); Wed, 4 Aug 2010 07:24:32 -0400 Received: from isilmar-3.linta.de ([188.40.101.200]:33401 "EHLO linta.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757404Ab0HDLYa (ORCPT ); Wed, 4 Aug 2010 07:24:30 -0400 Date: Wed, 4 Aug 2010 13:24:28 +0200 From: Dominik Brodowski To: Christoph Hellwig Cc: Michael Monnerie , linux-raid@vger.kernel.org, xfs@oss.sgi.com, linux-kernel@vger.kernel.org, dm-devel@redhat.com Subject: Re: How to track down abysmal performance ata - raid1 - crypto - vg/lv - xfs Message-ID: <20100804112428.GA5462@isilmar-3.linta.de> Mail-Followup-To: Dominik Brodowski , Christoph Hellwig , Michael Monnerie , linux-raid@vger.kernel.org, xfs@oss.sgi.com, linux-kernel@vger.kernel.org, dm-devel@redhat.com References: <20100804073546.GA7494@comet.dominikbrodowski.net> <20100804085039.GA11671@infradead.org> <20100804091317.GA27779@isilmar-3.linta.de> <20100804092122.GA2998@infradead.org> <20100804073546.GA7494@comet.dominikbrodowski.net> <201008041116.09822@zmi.at> <20100804102526.GB13766@isilmar-3.linta.de> <20100804111803.GA32643@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100804111803.GA32643@infradead.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1490 Lines: 36 On Wed, Aug 04, 2010 at 07:18:03AM -0400, Christoph Hellwig wrote: > On Wed, Aug 04, 2010 at 12:25:26PM +0200, Dominik Brodowski wrote: > > Hey, > > > > many thanks for your feedback. It seems the crypto step is the culprit: > > > > Reading 1.1 GB with dd, iflag=direct, bs=8k: > > > > /dev/sd* 35.3 MB/s ( 90 %) > > /dev/md* 39.1 MB/s (100 %) > > /dev/mapper/md*_crypt 3.9 MB/s ( 10 %) > > /dev/mapper/vg1-* 3.9 MB/s ( 10 %) > > > > The "good" news: it also happens on my notebook, even though it has a > > different setup (no raid, disk -> lv/vg -> crypt). On my notebook, I'm > > more than happy to test out different kernel versions, patches etc. > > > > /dev/sd* 17.7 MB/s (100 %) > > /dev/mapper/vg1-* 16.2 MB/s ( 92 %) > > /dev/mapper/*_crypt 3.1 MB/s ( 18 %) > > The good news is that you have it tracked down, the bad news is that > I know very little about dm-crypt. Maybe the issue is the single > threaded decryption in dm-crypt? Can you check how much CPU time > the dm crypt kernel thread uses? 2 CPUs overall: Cpu(s): 1.0%us, 5.7%sy, 0.0%ni, 44.8%id, 47.0%wa, 0.0%hi, 1.5%si, 0.0%st Thanks & best, Dominik -- 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/