Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751217Ab0FWJUh (ORCPT ); Wed, 23 Jun 2010 05:20:37 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:54815 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750967Ab0FWJUg (ORCPT ); Wed, 23 Jun 2010 05:20:36 -0400 Date: Wed, 23 Jun 2010 05:20:28 -0400 From: Christoph Hellwig To: Jeff Moyer Cc: axboe@kernel.dk, vgoyal@redhat.com, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org Subject: Re: [PATCH 0/3 v5][RFC] ext3/4: enhance fsync performance when using CFQ Message-ID: <20100623092028.GA13900@infradead.org> References: <1277242502-9047-1-git-send-email-jmoyer@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1277242502-9047-1-git-send-email-jmoyer@redhat.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1522 Lines: 30 On Tue, Jun 22, 2010 at 05:34:59PM -0400, Jeff Moyer wrote: > Hi, > > Running iozone with the fsync flag, or fs_mark, the performance of CFQ is > far worse than that of deadline for enterprise class storage when dealing > with file sizes of 8MB or less. I used the following command line as a > representative test case: > > fs_mark -S 1 -D 10000 -N 100000 -d /mnt/test/fs_mark -s 65536 -t 1 -w 4096 -F > > When run using the deadline I/O scheduler, an average of the first 5 numbers > will give you 448.4 files / second. CFQ will yield only 106.7. With > this patch series applied (and the two patches I sent yesterday), CFQ now > achieves 462.5 files / second. > > This patch set is still an RFC. I'd like to make it perform better when > there is a competing sequential reader present. For now, I've addressed > the concerns voiced about the previous posting. What happened to the initial idea of just using the BIO_RW_META flag for log writes? In the end log writes are the most important writes you have in a journaled filesystem, and they should not be effect to any kind of queue idling logic or other interruption. Log I/O is usually very little (unless you use old XFS code with a worst-case directory manipulation workload), and very latency sensitive. -- 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/