Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263518AbTKUNxv (ORCPT ); Fri, 21 Nov 2003 08:53:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264274AbTKUNxu (ORCPT ); Fri, 21 Nov 2003 08:53:50 -0500 Received: from intra.cyclades.com ([64.186.161.6]:62627 "EHLO intra.cyclades.com") by vger.kernel.org with ESMTP id S263518AbTKUNxs (ORCPT ); Fri, 21 Nov 2003 08:53:48 -0500 Date: Fri, 21 Nov 2003 11:47:49 -0200 (BRST) From: Marcelo Tosatti X-X-Sender: marcelo@logos.cnet To: Mikael Johansson Cc: linux-raid@vger.kernel.org, Subject: Re: RAID-0 read perf. decrease after 2.4.20 In-Reply-To: Message-ID: 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 Content-Length: 1362 Lines: 37 On Thu, 20 Nov 2003, Mikael Johansson wrote: > > Hello All! > > Has anyone else experienced a drastic drop in read performance on software > RAID-0 with post 2.4.20 kernels? We have a few Athlon XP's here at our > lab with double IDE disks on different channels set up as RAID-0. Some > bonnie++ benchmark results with various kernels, on the same machine > (Athlon XP 2400+, 2 GHz, 1.5 GB RAM, VIA chipset, 2*Maxtor 120 GB > 6Y060L0): > write read > 2.4.20-ac1: 88,000 135,000 K/sec > 2.4.21-pre7: 93,000 75,000 > 2.4.22-ac4: 94,000 82,000 > > So the write speed has gone up a bit, but the read speed performance has > plunged. Any ideas on what happened between 2.4.20 and 2.4.21 and what to > do about it? I'm eagerly awaiting suggestions, good read speed is quite > critical for many of our calculations :-) I will of course provide more > details if necessary. There have been no significant changes in the RAID driver in 2.4.21, so I suspect the cause for the slowdowns might the changes to the IO scheduler (ll_rw_blk.c) or VM changes. Isolating the -pre which the slowdown starts helps a lot. - 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/