Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755603AbYCNHfm (ORCPT ); Fri, 14 Mar 2008 03:35:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752053AbYCNHfe (ORCPT ); Fri, 14 Mar 2008 03:35:34 -0400 Received: from mga10.intel.com ([192.55.52.92]:1212 "EHLO fmsmga102.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751516AbYCNHfe (ORCPT ); Fri, 14 Mar 2008 03:35:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.25,499,1199692800"; d="scan'208";a="306171615" Subject: Re: hackbench regression since 2.6.25-rc From: "Zhang, Yanmin" To: Christoph Lameter Cc: Andrew Morton , Kay Sievers , Greg Kroah-Hartman , LKML , Ingo Molnar In-Reply-To: References: <1205394417.3215.85.camel@ymzhang> <20080313014808.f8d25c2a.akpm@linux-foundation.org> <1205400538.3215.148.camel@ymzhang> <1205463842.3215.188.camel@ymzhang> <1205465447.3215.195.camel@ymzhang> <1205472481.3215.268.camel@ymzhang> Content-Type: text/plain; charset=utf-8 Date: Fri, 14 Mar 2008 15:29:01 +0800 Message-Id: <1205479741.3215.293.camel@ymzhang> Mime-Version: 1.0 X-Mailer: Evolution 2.9.2 (2.9.2-2.fc7) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2115 Lines: 48 On Thu, 2008-03-13 at 23:39 -0700, Christoph Lameter wrote: > On Fri, 14 Mar 2008, Zhang, Yanmin wrote: > > > On tigerton, if I add "slub_max_order=3 slub_min_objects=16" to kernel > > boot cmdline, the result is improved significantly and it takes just > > 1/10 time of the original testing. > > Hmmm... That means the updates to SLUB in mm will fix the regression that > you are seeing because we there can use large orders of slabs and fallback > for all slab caches. But I am still interested to get to the details of > slub behavior on the 16p. > > > So kmalloc-512 is the key. > > Yeah in 2.6.26-rc kmalloc-512 has 8 objects per slab. The mm version > increases that with a larger allocation size. Would you like to give me a pointer to the patch? Is it one patch, or many patches? > > > Then, I tested it on stoakley with the same kernel commandline. > > Improvement is about 50%. One important thing is without the boot > > parameter, hackbench on stoakey takes only 1/4 time of the one on > > tigerton. With the boot parameter, hackbench on tigerton is faster than > > the one on stoakely. > > > > Is it possible to initiate slub_min_objects based on possible cpu > > number? I mean, cpu_possible_map(). We could calculate slub_min_objects > > by a formular. > > Hmmm... Interesting. Lets first get the details for 2.6.25-rc. Then we can > start toying around with the slub version in mm to configure slub in such > a way that we get best results on both machines. Boot parameter "slub_max_order=3 slub_min_objects=16" could boost perforamnce both on stoakley and on tigerton. So should we keep slub_min_objects scalable based on possible cpu number? When a machine has more cpu, it means more processes/threads will run on it and it will take more time when they compete for the same resources. SLAB is such a typical resource. -yanmin -- 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/