Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id <S282904AbRLMALa>; Wed, 12 Dec 2001 19:11:30 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org
	id <S282918AbRLMALV>; Wed, 12 Dec 2001 19:11:21 -0500
Received: from 12-234-19-19.client.attbi.com ([12.234.19.19]:50957 "HELO
	ocean.lucon.org") by vger.kernel.org with SMTP id <S282906AbRLMALE>;
	Wed, 12 Dec 2001 19:11:04 -0500
Date: Wed, 12 Dec 2001 16:11:02 -0800
From: "H . J . Lu" <hjl@lucon.org>
To: Andrea Arcangeli <andrea@suse.de>
Cc: linux kernel <linux-kernel@vger.kernel.org>
Subject: Re: Slow Disk I/O with QPS M3 80GB HD
Message-ID: <20011212161102.A22818@lucon.org>
In-Reply-To: <20011210203452.A3250@lucon.org> <20011210235708.A17743@lucon.org> <20011211154331.A32433@lucon.org> <20011212092954.N4801@athlon.random> <20011212153806.A22202@lucon.org> <20011213004933.T4801@athlon.random>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.2.5i
In-Reply-To: <20011213004933.T4801@athlon.random>; from andrea@suse.de on Thu, Dec 13, 2001 at 12:49:33AM +0100
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Dec 13, 2001 at 12:49:33AM +0100, Andrea Arcangeli wrote:
> On Wed, Dec 12, 2001 at 03:38:06PM -0800, H . J . Lu wrote:
> > H.J.
> > ----
> > 3 files on USB:
> > 
> > # ls -l
> > total 5984
> > -rwxr-xr-x    1 root     root      1991481 Dec  8 21:44 dsc00002.jpg
> > -rwxr-xr-x    1 root     root      2432127 Dec  8 23:54 dsc00005.jpg
> > -rwxr-xr-x    1 root     root      1675563 Dec  8 23:59 dsc00009.jpg
> > 
> > 1. 2.4.10-pre10
> > 
> > # time /bin/cp * /tmp/
> > real    0m0.623s
> > user    0m0.000s
> > sys     0m0.100s
> > 
> > 2. 2.4.10-pre10aa1

I applied all the way to 40_blkdev-pagecache-17 in 2.4.10-pre10aa1.

> > 
> > # time /bin/cp * /tmp/
> > real    0m8.952s
> > user    0m0.000s
> > sys     0m0.190s
> > 
> > 
> > 3. 2.4.10-pre11
> > 
> > # time /bin/cp * /tmp/
> > real    0m8.851s
> > user    0m0.000s
> > sys     0m0.170s
> 
> but the above have nothing to do with the blkdev-pagecache.
> Blkdev-pagecache can matter only with blkdev accesses, blkdev-pagecache
> cannot make any difference if the I/O passes through any fs (not via the
> block_dev layer) like in the above case.

That is why I said it was strange.

> 
> Can you try to take those cp under strace timestamp and see what's the
> syscall that blocks?

It blocks on read.


H.J.
-
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/