Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757920Ab0DBIFS (ORCPT ); Fri, 2 Apr 2010 04:05:18 -0400 Received: from mga10.intel.com ([192.55.52.92]:6468 "EHLO fmsmga102.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754426Ab0DBIFK (ORCPT ); Fri, 2 Apr 2010 04:05:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.51,352,1267430400"; d="scan'208";a="785992858" Subject: Re: hackbench regression due to commit 9dfc6e68bfe6e From: "Zhang, Yanmin" To: Christoph Lameter Cc: alex.shi@intel.com, "linux-kernel@vger.kernel.org" , "Ma, Ling" , "Chen, Tim C" , Tim C , Pekka Enberg , Andrew Morton In-Reply-To: References: <1269506457.4513.141.camel@alexs-hp.sh.intel.com> <1269570902.9614.92.camel@alexs-hp.sh.intel.com> <1270114166.2078.107.camel@ymzhang.sh.intel.com> Content-Type: text/plain; charset="ISO-8859-1" Date: Fri, 02 Apr 2010 16:06:29 +0800 Message-Id: <1270195589.2078.116.camel@ymzhang.sh.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.28.0 (2.28.0-2.fc12) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1219 Lines: 31 On Thu, 2010-04-01 at 10:53 -0500, Christoph Lameter wrote: > On Thu, 1 Apr 2010, Zhang, Yanmin wrote: > > > I suspect the moving of place of cpu_slab in kmem_cache causes the new cache > > miss. But when I move it to the tail of the structure, kernel always panic when > > booting. Perhaps there is another potential bug? > > Why would that cause an additional cache miss? > > > The node array is following at the end of the structure. If you want to > move it down then it needs to be placed before the node field Thanks. The moving cpu_slab to tail doesn't improve it. I used perf to collect statistics. Only data cache miss has a little difference. My testing command on my 2 socket machine: #hackbench 100 process 20000 With 2.6.33, it takes for about 96 seconds while 2.6.34-rc2 (or the latest tip tree) takes for about 101 seconds. perf shows some functions around SLUB have more cpu utilization, while some other SLUB functions have less cpu utilization. -- 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/