Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761274AbYCGC0I (ORCPT ); Thu, 6 Mar 2008 21:26:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764727AbYCGCZk (ORCPT ); Thu, 6 Mar 2008 21:25:40 -0500 Received: from ns2.suse.de ([195.135.220.15]:42865 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757253AbYCGCZj (ORCPT ); Thu, 6 Mar 2008 21:25:39 -0500 Date: Fri, 7 Mar 2008 03:25:37 +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: <20080307022537.GC21185@wotan.suse.de> References: <84144f020803031330i2c0ea1f6kc5b02c8b26145797@mail.gmail.com> <47CC6F30.50802@cs.helsinki.fi> <20080305002821.GD1510@wotan.suse.de> <20080306024904.GA27150@wotan.suse.de> <20080307020443.GA21185@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: 1123 Lines: 33 On Thu, Mar 06, 2008 at 06:20:40PM -0800, Christoph Lameter wrote: > On Fri, 7 Mar 2008, Nick Piggin wrote: > > > > Do you have a case in mind where that would be useful? We had a > > > > Patch 3/3 > > Those already have SLAB_HWCACHE_ALIGN. > > The point is to switch off alignment for UP? Cant we do that with > SLAB_HWCACHE_ALIGN too since SLOB seemed to work successfully without it > in the past? See my next post to correct your understanding of HWCACHE_ALIGN. > > > Note that there is also KMEM_CACHE which picks up the alignment from > > > the compiler. > > > > Yeah, that's not quite as good either. My allocation flag is dynamic, so > > it will not bloat things for no reason on UP machines and SMP kernels. > > It also aligns to the detected machine cacheline size rather than a > > compile time constant. > > Is that really a noteworthy effect? Yes. -- 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/