Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756134AbYCMQVT (ORCPT ); Thu, 13 Mar 2008 12:21:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752077AbYCMQVJ (ORCPT ); Thu, 13 Mar 2008 12:21:09 -0400 Received: from rgminet01.oracle.com ([148.87.113.118]:56006 "EHLO rgminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752216AbYCMQVG (ORCPT ); Thu, 13 Mar 2008 12:21:06 -0400 Date: Thu, 13 Mar 2008 09:19:21 -0700 From: Randy Dunlap To: Greg KH Cc: "Zhang, Yanmin" , Kay Sievers , LKML Subject: Re: hackbench regression since 2.6.25-rc Message-Id: <20080313091921.834d2532.randy.dunlap@oracle.com> In-Reply-To: <20080313151413.GA14045@suse.de> References: <1205394417.3215.85.camel@ymzhang> <20080313151413.GA14045@suse.de> Organization: Oracle Linux Eng. X-Mailer: Sylpheed 2.4.7 (GTK+ 2.8.10; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAQAAAAI= X-Brightmail-Tracker: AAAAAQAAAAI= X-Whitelist: TRUE X-Whitelist: TRUE Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1993 Lines: 45 On Thu, 13 Mar 2008 08:14:13 -0700 Greg KH wrote: > On Thu, Mar 13, 2008 at 03:46:57PM +0800, Zhang, Yanmin wrote: > > Comparing with 2.6.24, on my 16-core tigerton, hackbench process mode has about > > 40% regression with 2.6.25-rc1, and more than 20% regression with kernel > > 2.6.25-rc4, because rc4 includes the reverting patch of scheduler load balance. > > > > Command to start it. > > #hackbench 100 process 2000 > > I ran it for 3 times and sum the values. > > > > I tried to investiagte it by bisect. > > Kernel up to tag 0f4dafc0563c6c49e17fe14b3f5f356e4c4b8806 has the 20% regression. > > Kernel up to tag 6e90aa972dda8ef86155eefcdbdc8d34165b9f39 hasn't regression. > > > > Any bisect between above 2 tags cause kernel hang. I tried to checkout to a point between > > these 2 tags for many times manually and kernel always paniced. > > Where is the kernel panicing? The changeset right after the last one > above: bc87d2fe7a1190f1c257af8a91fc490b1ee35954, is a change to efivars, > are you using that in your .config? > > > All patches between the 2 tags are on kobject restructure. I guess such restructure > > creates more cache miss on the 16-core tigerton. > > Nothing should be creating kobjects on a normal load like this, so a > regression seems very odd. Unless the /sys/kernel/uids/ stuff is > triggering this? > > Do you have a link to where I can get hackbench (google seems to find > lots of reports with it, but not the source itself), so I can test to > see if we are accidentally creating kobjects with this load? The version that I see referenced most often (unscientifically :) is somewhere under people.redhat.com/mingo/, like so: http://people.redhat.com/mingo/cfs-scheduler/tools/hackbench.c --- ~Randy -- 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/