Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757552AbZFVQbk (ORCPT ); Mon, 22 Jun 2009 12:31:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752443AbZFVQbd (ORCPT ); Mon, 22 Jun 2009 12:31:33 -0400 Received: from stz-softwaretechnik.de ([217.160.223.211]:1455 "EHLO stlx01.stz-softwaretechnik.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751994AbZFVQbc (ORCPT ); Mon, 22 Jun 2009 12:31:32 -0400 Date: Mon, 22 Jun 2009 18:31:13 +0200 From: Ralf Gross To: linux-kernel@vger.kernel.org Subject: Re: io-scheduler tuning for better read/write ratio Message-ID: <20090622163113.GD12483@p15145560.pureserver.info> References: <20090616154342.GA7043@p15145560.pureserver.info> <4A37CB2A.6010209@davidnewall.com> <20090616184027.GB7043@p15145560.pureserver.info> <4A37E7DB.7030100@redhat.com> <20090616185600.GC7043@p15145560.pureserver.info> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1929 Lines: 49 Jeff Moyer schrieb: > Jeff Moyer writes: > > > Ralf Gross writes: > > > >> Casey Dahlin schrieb: > >>> On 06/16/2009 02:40 PM, Ralf Gross wrote: > >>> > David Newall schrieb: > >>> >> Ralf Gross wrote: > >>> >>> write throughput is much higher than the read throughput (40 MB/s > >>> >>> read, 90 MB/s write). > >>> > > >>> > Hm, but I get higher read throughput (160-200 MB/s) if I don't write > >>> > to the device at the same time. > >>> > > >>> > Ralf > >>> > >>> How specifically are you testing? It could depend a lot on the > >>> particular access patterns you're using to test. > >> > >> I did the basic tests with tiobench. The real test is a test backup > >> (bacula) with 2 jobs that create 2 30 GB spool files on that device. > >> The jobs partially write to the device in parallel. Depending which > >> spool file reaches the 30 GB first, one starts reading from that file > >> and writing to tape, while to other is still spooling. > > > > We are missing a lot of details, here. I guess the first thing I'd try > > would be bumping up the max_readahead_kb parameter, since I'm guessing > > that your backup application isn't driving very deep queue depths. If > > that doesn't work, then please provide exact invocations of tiobench > > that reprduce the problem or some blktrace output for your real test. > > Any news, Ralf? sorry for the delay. atm there are large backups running and using the raid device for spooling. So I can't do any tests. Re. read ahead: I tested different settings from 8Kb to 65Kb, this didn't help. I'll do some more tests when the backups are done (3-4 more days). Thanks, Ralf -- 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/