Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030628AbWAHJ5r (ORCPT ); Sun, 8 Jan 2006 04:57:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030629AbWAHJ5r (ORCPT ); Sun, 8 Jan 2006 04:57:47 -0500 Received: from willy.net1.nerim.net ([62.212.114.60]:39692 "EHLO willy.net1.nerim.net") by vger.kernel.org with ESMTP id S1030628AbWAHJ5q (ORCPT ); Sun, 8 Jan 2006 04:57:46 -0500 Date: Sun, 8 Jan 2006 10:57:41 +0100 From: Willy Tarreau To: Grant Coady Cc: Markus Rechberger , linux-kernel@vger.kernel.org Subject: Re: Why is 2.4.32 four times faster than 2.6.14.6?? Message-ID: <20060108095741.GH7142@w.ods.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.10i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3416 Lines: 70 Hi Grant, On Sun, Jan 08, 2006 at 06:28:53PM +1100, Grant Coady wrote: > On Sun, 8 Jan 2006 07:58:09 +0100, Markus Rechberger wrote: > > >Were there any other processes running during the test? > box runs same config both kernels: the usual light load ~100% idle ;) > >what does "vmstat 1" show up during the test? > > grant@deltree:~$ uname -r > 2.6.14.6a > grant@deltree:~$ vmstat 1 > procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- > r b swpd free buff cache si so bi bo in cs us sy id wa > [...] > 0 0 0 63800 11520 32352 0 0 0 0 110 18 0 0 100 0 > 0 0 0 63800 11520 32352 0 0 0 0 106 17 1 0 99 0 > 3 0 0 63560 11520 32352 0 0 0 0 346 502 22 9 69 0 > 1 0 0 63560 11520 32352 0 0 0 0 1057 1987 59 41 0 0 > 1 0 0 63560 11520 32352 0 0 0 0 1062 2011 59 41 0 0 > 1 0 0 63560 11520 32352 0 0 0 0 1053 2001 50 50 0 0 > 1 0 0 63500 11596 32352 0 0 0 136 1054 1974 61 39 0 0 > 1 0 0 63500 11596 32352 0 0 0 0 1040 1978 50 50 0 0 > 0 0 0 63620 11596 32352 0 0 0 0 799 1425 45 27 29 0 > 0 0 0 63620 11596 32352 0 0 0 0 104 12 0 0 100 0 > 0 0 0 63620 11596 32352 0 0 0 0 103 10 0 0 100 0 > > grant@deltree:~$ uname -r > 2.4.32-hf32.1 > grant@deltree:~$ vmstat 1 > procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- > r b swpd free buff cache si so bi bo in cs us sy id wa > [...] > 0 0 0 83192 6532 21404 0 0 0 0 104 12 0 1 99 0 > 0 0 0 83152 6572 21404 0 0 0 80 116 24 0 1 99 0 > 1 0 0 82952 6572 21404 0 0 0 0 168 130 6 5 89 0 > 2 0 0 82952 6572 21404 0 0 0 0 667 1019 65 35 0 0 > 0 0 0 83152 6572 21404 0 0 0 0 297 378 41 10 49 0 > 0 0 0 83152 6572 21404 0 0 0 0 104 9 0 1 99 0 > 0 0 0 83064 6656 21404 0 0 0 304 169 121 0 1 99 0 > 0 0 0 83064 6656 21404 0 0 0 0 137 42 0 2 98 0 It's rather strange that 2.6 *eats* CPU apparently doing nothing ! At first I thought about a PIO/DMA problemn but we can clearly see that there's no IO in on both vmstat. Could you please retest : - without the pipe (remove '| cut ...') to avoid inter-process communications - with cat instead of grep to ensure you don't spend time processing anything You should be able to find one simple pattern which makes the problem appear/disappear on 2.6. At least, 'cat x.log >/dev/null' should not take time or that time should be spent in I/O. I remember an old test I did a long time ago which behaved badly on 2.6, it consisted in lots of pipes (eg: dd bs=1 | dd bs=1 |...). May be you're on a simplified form of this. > -- > Thanks, > Grant. > http://bugsplatter.mine.nu/ Cheers, Willy - 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/