From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 26 Aug 2001 17:13:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 26 Aug 2001 17:13:38 -0400 Received: from humbolt.nl.linux.org ([131.211.28.48]:15373 "EHLO humbolt.nl.linux.org") by vger.kernel.org with ESMTP id ; Sun, 26 Aug 2001 17:13:34 -0400 Content-Type: text/plain; charset="iso-8859-1" From: Daniel Phillips To: =?iso-8859-1?q?G=E9rard=20Roudier=20?= Subject: Re: [resent PATCH] Re: very slow parallel read performance Date: Sun, 26 Aug 2001 23:20:24 +0200 X-Mailer: KMail [version 1.3.1] Cc: , Rik van Riel , Alan Cox , Roger Larsson , In-Reply-To: <20010826220717.E16170-100000@gerard> In-Reply-To: <20010826220717.E16170-100000@gerard> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-Id: <20010826211349Z16294-32384+570@humbolt.nl.linux.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On August 26, 2001 10:26 pm, Gérard Roudier wrote: > On Sun, 26 Aug 2001, Daniel Phillips wrote: > > [...] > > > It should not be being ignored. This needs to be looked into. In any event, > > the max-readahead proc setting is clearly good and needs to be in Linus's > > tree, otherwise changing the default MAX_READAHEAD requires a recompile. > > Worse, there is no way at all to specify the kernel's max-readahead for scsi > > disks - regardless of the fact that scsi disks do their own readahead, the > > kernel will do its own as well, with no way for the user to turn it off. > > For SCSI disks prefetch tuning you may look into the CACHING page. > > For example, you can tell the drive to stop prefetching as soon a command > is ready by setting MINIMUM PRE-FETCH to zero. > > Unfortunately, not all SCSI disks allow to tune all the configuration > parameters of the caching page. In this case he's using ide. -- Daniel