Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754658AbXHVA00 (ORCPT ); Tue, 21 Aug 2007 20:26:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751233AbXHVA0T (ORCPT ); Tue, 21 Aug 2007 20:26:19 -0400 Received: from tomts25.bellnexxia.net ([209.226.175.188]:51778 "EHLO tomts25-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751007AbXHVA0S (ORCPT ); Tue, 21 Aug 2007 20:26:18 -0400 Date: Tue, 21 Aug 2007 20:26:16 -0400 From: Mathieu Desnoyers To: Christoph Lameter Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, mingo@redhat.com Subject: Re: [PATCH] SLUB use cmpxchg_local Message-ID: <20070822002616.GA1400@Krystal> References: <20070821173849.GA8360@Krystal> <20070821231216.GA29691@Krystal> <20070821233938.GD29691@Krystal> <20070821234702.GE29691@Krystal> <20070822000323.GG29691@Krystal> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 20:16:02 up 23 days, 34 min, 3 users, load average: 0.34, 0.40, 0.36 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1428 Lines: 35 * Christoph Lameter (clameter@sgi.com) wrote: > On Tue, 21 Aug 2007, Mathieu Desnoyers wrote: > > > - Rounding error.. you seem to round at 0.1ms, but I keep the values in > > cycles. The times that you get (1.1ms) seems strangely higher than > > mine, which are under 1000 cycles on a 3GHz system (less than 333ns). > > I guess there is both a ms - ns error there and/or not enough > > precision in your numbers. > > Nope the rounding for output is depending on the amount. Rounds to one > digit after whatever unit we figured out is best to display. > > And multiplications (cyc2ns) do not result in rounding errors. > Ok, I see now that the 1.1ms was for the 10000 iterations, which makes it about 230 ns/iteration for the 10000 times kmalloc(8) = 2.3ms test. As I am going back through the initial cmpxchg_local implementation, it seems like it was executing __slab_alloc() with preemption disabled, which is wrong. new_slab() is not designed for that. I'll try to run my tests on AMD64. Mathieu -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 - 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/