Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261873AbTKCAQF (ORCPT ); Sun, 2 Nov 2003 19:16:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261875AbTKCAQF (ORCPT ); Sun, 2 Nov 2003 19:16:05 -0500 Received: from h24-76-142-122.wp.shawcable.net ([24.76.142.122]:41738 "HELO signalmarketing.com") by vger.kernel.org with SMTP id S261873AbTKCAQC (ORCPT ); Sun, 2 Nov 2003 19:16:02 -0500 Date: Sun, 2 Nov 2003 18:15:56 -0600 (CST) From: Derek Foreman X-X-Sender: manmower@uberdeity To: Andrew Morton cc: ahuisman@cistron.nl, linux-kernel@vger.kernel.org, nuno.silva@vgertech.com Subject: Re: READAHEAD In-Reply-To: <20031031012946.3adedc14.akpm@osdl.org> Message-ID: References: <20031030134407.0c97c86e.akpm@osdl.org> <3FA25377.3050207@cistron.nl> <20031031012846.48fa233c.akpm@osdl.org> <20031031012946.3adedc14.akpm@osdl.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1953 Lines: 55 On Fri, 31 Oct 2003, Andrew Morton wrote: > Andrew Morton wrote: > > > > Please, just use time, cat, dd, etc. > > > > mount /dev/xxx /mnt/yyy > > dd if=/dev/zero of=/mnt/yyy/x bs=1M count=1024 > > umount /dev/xxx > > mount /dev/xxx /mnt/yyy > > time cat /mnt/yyy/x > /dev/null > > And you can do the same against /dev/hdaN if you have a scratch > partition; that would be interesting. I don't have a scratch partition, but the effect is quite apparent when reading from /dev/hd* I have 384 megs of ram, no swap, and echo 0 > /proc/sys/vm/swappiness kernel is 2.6.0-test9 hdparm -qa 0 /dev/hde ; dd if=/dev/hde of=/dev/null bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes transferred in 103.038178 seconds (10420815 bytes/sec) hdparm -qa 128 /dev/hde ; dd if=/dev/hde of=/dev/null bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes transferred in 34.171719 seconds (31421943 bytes/sec) hdparm -qa 256 /dev/hde ; dd if=/dev/hde of=/dev/null bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes transferred in 34.994348 seconds (30683293 bytes/sec) hdparm -qa 4096 /dev/hde ; dd if=/dev/hde of=/dev/null bs=1M count=1024 1024+0 records in 1024+0 records out 1073741824 bytes transferred in 22.268371 seconds (48218247 bytes/sec) (hdparm -t /dev/hde opens /dev/hde and reads it for a few seconds, so these numbers are much the same as my hdparm -t scores) I also get similar results from /dev/md0 in another machine (the only not-ide device I can test on... but it's still a bunch of ide drives). note... For people playing with hdparm, hdparm -a 123 -t /dev/drive doesn't set the readahead before running the test. - 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/