From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Zhang, Yanmin" Subject: Re: tbench regression on each kernel release from 2.6.22 -> 2.6.28 Date: Mon, 18 Aug 2008 10:05:14 +0800 Message-ID: <1219025114.25933.6.camel@ymzhang> References: <48A086B6.2000901@linux-foundation.org> <20080811.141501.01468546.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Miller , cl@linux-foundation.org, Netdev , LKML To: Ilpo =?ISO-8859-1?Q?J=E4rvinen?= Return-path: Received: from mga05.intel.com ([192.55.52.89]:11477 "EHLO fmsmga101.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750943AbYHRCGH (ORCPT ); Sun, 17 Aug 2008 22:06:07 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2008-08-12 at 11:13 +0300, Ilpo J=E4rvinen wrote:=20 > On Mon, 11 Aug 2008, David Miller wrote: >=20 > > From: Christoph Lameter > > Date: Mon, 11 Aug 2008 13:36:38 -0500 > >=20 > > > It seems that the network stack becomes slower over time? Here is= a list of > > > tbench results with various kernel versions: > > >=20 > > > 2.6.22 3207.77 mb/sec > > > 2.6.24 3185.66 > > > 2.6.25 2848.83 > > > 2.6.26 2706.09 > > > 2.6.27(rc2) 2571.03 > > >=20 > > > And linux-next is: > > >=20 > > > 2.6.28(l-next) 2568.74 > > >=20 > > > It shows that there is still have work to be done on linux-next. = Too close to > > > upstream in performance. > > >=20 > > > Note the KT event between 2.6.24 and 2.6.25. Why is that? > >=20 > > Isn't that when some major scheduler changes went in? I'm not blam= ing > > the scheduler, but rather I'm making the point that there are other > > subsystems in the kernel that the networking interacts with that > > influences performance at such a low level. >=20 > ...IIRC, somebody in the past did even bisect his (probably netperf)=20 > 2.6.24-25 regression to some scheduler change (obviously it might or = might=20 > not be related to this case of yours)... I did find much regression with netperf TCP-RR-1/UDP-RR-1/UDP-RR-512. I= start 1 serve and 1 client while binding them to a different logical processo= r in different physical cpu. Comparing with 2.6.22, the regression of TCP-RR-1 on 16-core tigerton i= s: 2.6.23 6% 2.6.24 6% 2.6.25 9.7% 2.6.26 14.5% 2.6.27-rc1 22% Other regressions on other machines are similar. yanmin