Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752891AbYCMIsn (ORCPT ); Thu, 13 Mar 2008 04:48:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751270AbYCMIsf (ORCPT ); Thu, 13 Mar 2008 04:48:35 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:45100 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750929AbYCMIse (ORCPT ); Thu, 13 Mar 2008 04:48:34 -0400 Date: Thu, 13 Mar 2008 01:48:08 -0700 From: Andrew Morton To: "Zhang, Yanmin" Cc: Kay Sievers , Greg Kroah-Hartman , LKML , Ingo Molnar Subject: Re: hackbench regression since 2.6.25-rc Message-Id: <20080313014808.f8d25c2a.akpm@linux-foundation.org> In-Reply-To: <1205394417.3215.85.camel@ymzhang> References: <1205394417.3215.85.camel@ymzhang> X-Mailer: Sylpheed 2.3.1 (GTK+ 2.10.11; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1389 Lines: 31 On Thu, 13 Mar 2008 15:46:57 +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. > > All patches between the 2 tags are on kobject restructure. I guess such restructure > creates more cache miss on the 16-core tigerton. > That's pretty surprising - hackbench spends most of its time in userspace and zeroing out anonymous pages. It shouldn't be fiddling with kobjects much at all. Some kernel profiling might be needed here.. -- 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/