From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753928AbXDJV6c (ORCPT ); Tue, 10 Apr 2007 17:58:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753930AbXDJV6b (ORCPT ); Tue, 10 Apr 2007 17:58:31 -0400 Received: from mail.suse.de ([195.135.220.2]:45855 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753928AbXDJV6a (ORCPT ); Tue, 10 Apr 2007 17:58:30 -0400 To: Jan Kara Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, npiggin@suse.de Subject: Re: [PATCH] Improve heuristic detecting sequential reads References: <20070410155411.GF13445@duck.suse.cz> From: Andi Kleen Date: 11 Apr 2007 00:56:51 +0200 In-Reply-To: <20070410155411.GF13445@duck.suse.cz> Message-ID: User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3 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 Jan Kara writes: > Hello! > > In thread http://lkml.org/lkml/2007/3/9/403, we discussed a problem > with the current heuristic for detecting sequential IO in > do_generic_mapping_read() - for small files a page is marked as accessed > only once which can cause a performance problems. > Attached is a patch that improves the heuristic by introducing a > ra.offset variable so now we can reliably detect sequetial reads. > The patch replaces Nick's patch from http://lkml.org/lkml/2007/3/15/177 > (Nick has acked to replace the patch). Could you please put the patch > into -mm? There's a much more complete patchkit for this that gets reposted regularly on l-k. Perhaps it would make sense to test that first? -Andi