Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762278AbXJEMik (ORCPT ); Fri, 5 Oct 2007 08:38:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753174AbXJEMib (ORCPT ); Fri, 5 Oct 2007 08:38:31 -0400 Received: from brick.kernel.dk ([87.55.233.238]:28350 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752135AbXJEMia (ORCPT ); Fri, 5 Oct 2007 08:38:30 -0400 Date: Fri, 5 Oct 2007 14:39:53 +0200 From: Jens Axboe To: Andi Kleen Cc: Pekka Enberg , David Chinner , David Miller , cebbert@redhat.com, willy@linux.intel.com, clameter@sgi.com, nickpiggin@yahoo.com.au, hch@lst.de, mel@skynet.ie, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, suresh.b.siddha@intel.com Subject: Re: SLUB performance regression vs SLAB Message-ID: <20071005123953.GS5711@kernel.dk> References: <470554D9.2050505@redhat.com> <20071004.141113.08322956.davem@davemloft.net> <47055F84.109@redhat.com> <20071004.150718.95506800.davem@davemloft.net> <20071004222356.GH23367404@sgi.com> <20071005064853.GI5711@kernel.dk> <84144f020710050219k2460631cjfd556d6eae645887@mail.gmail.com> <20071005092822.GL5711@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1200 Lines: 30 On Fri, Oct 05 2007, Andi Kleen wrote: > Jens Axboe writes: > > > > Writing a small test module to exercise slub/slab in various ways > > (allocating from all cpus freeing from one, as described) should not be > > too hard. Perhaps that would be enough to find this performance > > discrepancy between slab and slub? > > You could simulate that by just sending packets using unix sockets > between threads bound to different CPUs. Sending a packet allocates; > receiving deallocates. Sure, there are a host of ways to accomplish the same thing. > But it's not clear that will really simulate the cache bounce > environment of the database test. I don't think all passing of data > between CPUs using slub objects is slow. It might not, it might. The point is trying to isolate the problem and making a simple test case that could be used to reproduce it, so that Christoph (or someone else) can easily fix it. -- Jens Axboe - 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/