From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265840AbUGDX2d (ORCPT ); Sun, 4 Jul 2004 19:28:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S265841AbUGDX2d (ORCPT ); Sun, 4 Jul 2004 19:28:33 -0400 Received: from send.it.helsinki.fi ([128.214.205.133]:391 "EHLO send.it.helsinki.fi") by vger.kernel.org with ESMTP id S265840AbUGDX2Y (ORCPT ); Sun, 4 Jul 2004 19:28:24 -0400 Date: Mon, 5 Jul 2004 02:28:15 +0300 (EEST) From: Mikael Johansson X-X-Sender: mpjohans@soul.it.helsinki.fi To: Martin Knoblauch cc: Marcelo Tosatti , linux-kernel@vger.kernel.org Subject: Re: RAID-0 read perf. decrease after 2.4.20 In-Reply-To: <20031218143741.25747.qmail@web13908.mail.yahoo.com> Message-ID: References: <20031218143741.25747.qmail@web13908.mail.yahoo.com> 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 Hello again! Finally had time to test this on IDE, "better late than even later"... On Thu, 18 Dec 2003, Martin Knoblauch wrote: > > > Just some feedback: > > > > > > echo 511 > /proc/sys/vm/max-readahead > > > > > > brings back the read performance of my 30 disks on 4 controller > > > LVM/RAID0. > > > > Great. > > > > Indeed :-) Just to clarify - the modification of max-readahead was > sufficient to "fix" the observed read performance degradation. I did > not apply (or reverse) anything on top of 2.4.22. > > Actually 255 would have been sufficient, 511 proved to be a small bit > better :-)) The "max-readahead" does not seem to affect IDE-RAID, at least not with the 2.4.27-pre6 I just compiled on two machines. So the problem still exists, read speed on 2.4.20-ac2 is almost twice as fast as on later kernels :-/ Have a nice summer, Mikael J. http://www.helsinki.fi/~mpjohans/