Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756196AbYCMPOc (ORCPT ); Thu, 13 Mar 2008 11:14:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753081AbYCMPOX (ORCPT ); Thu, 13 Mar 2008 11:14:23 -0400 Received: from mx2.suse.de ([195.135.220.15]:41923 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752078AbYCMPOX (ORCPT ); Thu, 13 Mar 2008 11:14:23 -0400 Date: Thu, 13 Mar 2008 08:14:13 -0700 From: Greg KH To: "Zhang, Yanmin" Cc: Kay Sievers , LKML Subject: Re: hackbench regression since 2.6.25-rc Message-ID: <20080313151413.GA14045@suse.de> References: <1205394417.3215.85.camel@ymzhang> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1205394417.3215.85.camel@ymzhang> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1704 Lines: 39 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? thanks, greg k-h -- 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/