Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id <S289377AbSAJKW7>; Thu, 10 Jan 2002 05:22:59 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org
	id <S289376AbSAJKWs>; Thu, 10 Jan 2002 05:22:48 -0500
Received: from ns.virtualhost.dk ([195.184.98.160]:64272 "EHLO virtualhost.dk")
	by vger.kernel.org with ESMTP id <S289375AbSAJKWj>;
	Thu, 10 Jan 2002 05:22:39 -0500
Date: Thu, 10 Jan 2002 11:22:25 +0100
From: Jens Axboe <axboe@suse.de>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Badari Pulavarty <pbadari@us.ibm.com>, Benjamin LaHaise <bcrl@redhat.com>,
        linux-kernel@vger.kernel.org, marcelo@conectiva.com.br
Subject: Re: [PATCH] PAGE_SIZE IO for RAW (RAW VARY)
Message-ID: <20020110112225.S19814@suse.de>
In-Reply-To: <20020109132148.C12609@redhat.com> <200201091928.g09JSdH23535@eng2.beaverton.ibm.com> <20020110111825.C3357@inspiron.school.suse.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20020110111825.C3357@inspiron.school.suse.de>
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Jan 10 2002, Andrea Arcangeli wrote:
> On Wed, Jan 09, 2002 at 11:28:39AM -0800, Badari Pulavarty wrote:
> > Ben,
> > 
> > By any chance do you have a list of drivers that assume this ? 
> > What does it take to fix them ? 
> > 
> > I think Jens BIO changes for 2.5 will fix this problem. But 
> > 2.4 needs a solution in this area too. This patch showed 
> > significant improvement for database workloads. 
> 
> I didn't checked the implementation but as far as the blkdev is
> concerned the b_size changes without notification as soon as you 'mkfs
> -b somethingelse' and then mount the fs. So it cannot break as far I can
> tell. The only important thing is that b_size stays between 512 and 4k.

The concern is/was differently sized buffer_heads in the same request,
ie b_size changing as you iterate through the chunks of one request.

-- 
Jens Axboe

-
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/