From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: SLUB performance regression vs SLAB Date: Thu, 4 Oct 2007 11:32:24 -0700 Message-ID: <20071004183224.GA8641@linux.intel.com> References: <20070919033605.785839297@sgi.com> <200709280742.38262.nickpiggin@yahoo.com.au> <200709281514.48293.nickpiggin@yahoo.com.au> <20071004161621.GO12049@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Nick Piggin , Christoph Hellwig , Mel Gorman , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, David Chinner , Jens Axboe To: Christoph Lameter Return-path: Received: from mga07.intel.com ([143.182.124.22]:48837 "EHLO azsmga101.ch.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755966AbXJDRpu (ORCPT ); Thu, 4 Oct 2007 13:45:50 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Thu, Oct 04, 2007 at 10:38:15AM -0700, Christoph Lameter wrote: > On Thu, 4 Oct 2007, Matthew Wilcox wrote: > > > So, on "a well-known OLTP benchmark which prohibits publishing absolute > > numbers" and on an x86-64 system (I don't think exactly which model > > is important), we're seeing *6.51%* performance loss on slub vs slab. > > This is with a 2.6.23-rc3 kernel. Tuning the boot parameters, as you've > > asked for before (slub_min_order=2, slub_max_order=4, slub_min_objects=8) > > gets back 0.38% of that. It's still down 6.13% over slab. > > Yeah the fastpath vs. slow path is not the issue as Siddha and I concluded > earlier. Seems that we are mainly seeing cacheline bouncing due to two > cpus accessing meta data in the same page struct. The patches in > MM that are scheduled to be merged for .24 address that issue. I > have repeatedly asked that these patches be tested. The patches were > posted months ago. I just checked with the guys who did the test. When I said -rc3, I mis-spoke; this is 2.6.23-rc3 *plus* the patches which Suresh agreed to test for you.