From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 20 Sep 2001 12:16:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 20 Sep 2001 12:16:08 -0400 Received: from h24-64-71-161.cg.shawcable.net ([24.64.71.161]:54012 "EHLO webber.adilger.int") by vger.kernel.org with ESMTP id ; Thu, 20 Sep 2001 12:15:50 -0400 From: Andreas Dilger Date: Thu, 20 Sep 2001 10:15:44 -0600 To: Beau Kuiper Cc: Chris Mason , linux-kernel@vger.kernel.org Subject: Re: [PATCH] Significant performace improvements on reiserfs systems, kupdated bugfixes Message-ID: <20010920101544.A14526@turbolinux.com> Mail-Followup-To: Beau Kuiper , Chris Mason , linux-kernel@vger.kernel.org In-Reply-To: <391950000.1000988162@tiny> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.20i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sep 20, 2001 23:20 +0800, Beau Kuiper wrote: > Patch 3 doesn't improve performace much (even in theory the number of > dirty buffers being wrongly flushed is pretty low) Actually, it _may_ even make performance worse (hard to say). Consider the case where the "young" dirty buffers are in the same area of the disk as the "old" dirty buffers. Once you are forced to write the "old" buffers, you pretty much get to write the new buffers for free (low seek overhead). They _could_ be merged in the elevator code. Sadly, it is hard to tell whether this is possible or not, because the code to do these things live in different places. Maybe we could have an "optimistic" elevator merge, which only added "young" buffers if they merged with other old buffers. Cheers, Andreas -- Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto, \ would they cancel out, leaving him still hungry?" http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- Dogbert