From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q0VLqEH7102122 for ; Tue, 31 Jan 2012 15:52:14 -0600 Received: from smtp.pobox.com (b-pb-sasl-quonix.pobox.com [208.72.237.35]) by cuda.sgi.com with ESMTP id gOGGwHs0M9gTqAf7 for ; Tue, 31 Jan 2012 13:52:13 -0800 (PST) Date: Tue, 31 Jan 2012 21:52:10 +0000 From: Brian Candler Subject: Re: Performance problem - reads slower than writes Message-ID: <20120131215210.GB47420@soundmouse.com> References: <20120130220019.GA45782@nsrc.org> <20120131020508.GF9090@dastard> <20120131103126.GA46170@nsrc.org> <20120131145205.GA6607@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20120131145205.GA6607@infradead.org> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Christoph Hellwig Cc: xfs@oss.sgi.com On Tue, Jan 31, 2012 at 09:52:05AM -0500, Christoph Hellwig wrote: > You don't just read a single file at a time but multiple ones, don't > you? It's sequential at the moment, although I'll do further tests with the -c (concurrency) option to bonnie++ > Try playing with the following tweaks to get larger I/O to the disk: > > a) make sure you use the noop or deadline elevators > b) increase /sys/block/sdX/queue/max_sectors_kb from its low default > c) dramatically increase /sys/devices/virtual/bdi/:/read_ahead_kb Thank you very much: I will do further tests with these. Is the read_ahead_kb knob aware of file boundaries? That is, is there any risk that if I set it too large it would read useless blocks past the end of the file? Regards, Brian. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs