Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933591AbYCFCt0 (ORCPT ); Wed, 5 Mar 2008 21:49:26 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762832AbYCFCtI (ORCPT ); Wed, 5 Mar 2008 21:49:08 -0500 Received: from mx2.suse.de ([195.135.220.15]:42299 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755875AbYCFCtH (ORCPT ); Wed, 5 Mar 2008 21:49:07 -0500 Date: Thu, 6 Mar 2008 03:49:04 +0100 From: Nick Piggin To: Christoph Lameter Cc: Pekka Enberg , netdev@vger.kernel.org, Linux Kernel Mailing List , yanmin_zhang@linux.intel.com, David Miller , Eric Dumazet Subject: Re: [rfc][patch 1/3] slub: fix small HWCACHE_ALIGN alignment Message-ID: <20080306024904.GA27150@wotan.suse.de> References: <20080303200613.GC8974@wotan.suse.de> <20080303201701.GF8974@wotan.suse.de> <84144f020803031330i2c0ea1f6kc5b02c8b26145797@mail.gmail.com> <47CC6F30.50802@cs.helsinki.fi> <20080305002821.GD1510@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1168 Lines: 28 On Wed, Mar 05, 2008 at 12:56:33PM -0800, Christoph Lameter wrote: > On Wed, 5 Mar 2008, Nick Piggin wrote: > > > It started out as a SLUB regression that was exposing poor code in the > > percpu allocator due to different SLUB kmalloc alignments. That prompted > > That was due to SLUB's support for smaller allocation sizes. AFAICT has > nothing to do with alignment. The smaller sizes meant objects were less often aligned on cacheline boundaries. > > The SMP flag was just an RFC. I think some people (like Christoph) were > > being confused about the HWCACHE_ALIGN flag being for avoiding false > > sharing on SMP systems. It would actually be also generally useful to > > have the SMP flag (eg. see the sites I added it to in patch #3). > > Hmmm. We could define a global constant for that? Determine it on bootup > and then pass it as an alignment parameter? We could, but I'd rather just use the flag. -- 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/