Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932633Ab0HDLxI (ORCPT ); Wed, 4 Aug 2010 07:53:08 -0400 Received: from swm.pp.se ([212.247.200.143]:50849 "EHLO uplift.swm.pp.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757404Ab0HDLxG (ORCPT ); Wed, 4 Aug 2010 07:53:06 -0400 Date: Wed, 4 Aug 2010 13:53:03 +0200 (CEST) From: Mikael Abrahamsson To: Christoph Hellwig cc: Dominik Brodowski , 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 In-Reply-To: <20100804111803.GA32643@infradead.org> Message-ID: 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> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) Organization: People's Front Against WWW MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1054 Lines: 23 On Wed, 4 Aug 2010, Christoph Hellwig wrote: > 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? I'm not sure it's that. I have a Core i5 with AES-NI and that didn't significantly increase my overall performance, as it's not there the bottleneck is (at least in my system). I earlier sent out an email wondering if someone could shed some light on how scheduling, block caching and read-ahead works together when one does disks->md->crypto->lvm->fs, becase that's a lot of layers and potentially a lot of unneeded buffering, readahead and scheduling magic? -- Mikael Abrahamsson email: swmike@swm.pp.se -- 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/