Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752565AbYCLGWy (ORCPT ); Wed, 12 Mar 2008 02:22:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751918AbYCLGWo (ORCPT ); Wed, 12 Mar 2008 02:22:44 -0400 Received: from relay1.sgi.com ([192.48.171.29]:52990 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751882AbYCLGWn (ORCPT ); Wed, 12 Mar 2008 02:22:43 -0400 Date: Tue, 11 Mar 2008 23:21:58 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Nick Piggin cc: netdev@vger.kernel.org, Linux Kernel Mailing List , yanmin_zhang@linux.intel.com, David Miller , Eric Dumazet Subject: Re: [rfc][patch 2/3] slab: introduce SMP alignment In-Reply-To: <20080311071330.GA20271@wotan.suse.de> Message-ID: References: <20080303200355.GB8974@wotan.suse.de> <20080303201211.GE8974@wotan.suse.de> <20080303202411.GH8974@wotan.suse.de> <20080307043700.GI21185@wotan.suse.de> <20080307051944.GJ21185@wotan.suse.de> <20080311071330.GA20271@wotan.suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1299 Lines: 27 On Tue, 11 Mar 2008, Nick Piggin wrote: > On Thu, Mar 06, 2008 at 09:26:24PM -0800, Christoph Lameter wrote: > > Internode alignment is 4k. If you need an object aligned like that then it > > may be better to go to the page allocator. > > I never got a reply about this. Again: how can the modern slab allocator > avoid the need for internode alignment in order to prevent cacheline > pingpong on vsmp? Because I'm going to resubmit the SMP_ALIGN patch. You quoted my answer. Use the page allocator to allocate data that has an alignment requirement on a 4k boundary. > Also, the last I heard about the HWCACHE_ALIGN from you is that it didn't > make sense... I see it's merged now, which I appreciate, but I think it is > really important that we're on the same page here, so let me know if it > still doesn't make sense. I still think that the semantics are weird because it only works sometimes and then performs an alignment within a cacheline that improves the situation somewhat in some cases but does not give the user what he expected. -- 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/