Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756205AbYJYXLl (ORCPT ); Sat, 25 Oct 2008 19:11:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756273AbYJYXLA (ORCPT ); Sat, 25 Oct 2008 19:11:00 -0400 Received: from twin.jikos.cz ([213.151.79.26]:54653 "EHLO twin.jikos.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756528AbYJYXK6 (ORCPT ); Sat, 25 Oct 2008 19:10:58 -0400 Date: Sun, 26 Oct 2008 01:10:19 +0200 (CEST) From: Jiri Kosina X-X-Sender: jikos@twin.jikos.cz To: David Miller cc: efault@gmx.de, rjw@sisk.pl, Ingo Molnar , s0mbre@tservice.net.ru, a.p.zijlstra@chello.nl, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [tbench regression fixes]: digging out smelly deadmen. In-Reply-To: <20081025.002420.82739316.davem@davemloft.net> Message-ID: References: <20081024.221653.23695396.davem@davemloft.net> <1224914333.3822.18.camel@marge.simson.net> <1224917623.4929.15.camel@marge.simson.net> <20081025.002420.82739316.davem@davemloft.net> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1728 Lines: 46 On Sat, 25 Oct 2008, David Miller wrote: > But note that tbench performance improved a bit in 2.6.25. > In my tests I noticed a similar effect, but from 2.6.23 to 2.6.24, > weird. > Just for the public record here are the numbers I got in my testing. I have been currently looking at very similarly looking issue. For the public record, here are the numbers we have been able to come up with so far (measured with dbench, so the absolute values are slightly different, but still shows similar pattern) 208.4 MB/sec -- vanilla 2.6.16.60 201.6 MB/sec -- vanilla 2.6.20.1 172.9 MB/sec -- vanilla 2.6.22.19 74.2 MB/sec -- vanilla 2.6.23 46.1 MB/sec -- vanilla 2.6.24.2 30.6 MB/sec -- vanilla 2.6.26.1 I.e. huge drop for 2.6.23 (this was with default configs for each respective kernel). 2.6.23-rc1 shows 80.5 MB/s, i.e. a few % better than final 2.6.23, but still pretty bad. I have gone through the commits that went into -rc1 and tried to figure out which one could be responsible. Here are the numbers: 85.3 MB/s for 2ba2d00363 (just before on-deman readahead has been merged) 82.7 MB/s for 45426812d6 (before cond_resched() has been added into page 187.7 MB/s for c1e4fe711a4 (just before CFS scheduler has been merged) invalidation code) So the current bigest suspect is CFS, but I don't have enough numbers yet to be able to point a finger to it with 100% certainity. Hopefully soon. Just my $0.02 -- Jiri Kosina SUSE Labs -- 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/