Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752646Ab0GFO1q (ORCPT ); Tue, 6 Jul 2010 10:27:46 -0400 Received: from hera.kernel.org ([140.211.167.34]:53721 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751114Ab0GFO1p (ORCPT ); Tue, 6 Jul 2010 10:27:45 -0400 Message-ID: <4C333D09.10204@kernel.org> Date: Tue, 06 Jul 2010 16:26:17 +0200 From: Tejun Heo User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); en-US; rv:1.9.2.4) Gecko/20100608 Thunderbird/3.1 MIME-Version: 1.0 To: Christoph Lameter CC: Frederic Weisbecker , torvalds@linux-foundation.org, mingo@elte.hu, linux-kernel@vger.kernel.org, jeff@garzik.org, akpm@linux-foundation.org, rusty@rustcorp.com.au, dhowells@redhat.com, arjan@linux.intel.com, oleg@redhat.com, axboe@kernel.dk, dwalker@codeaurora.org, stefanr@s5r6.in-berlin.de, florian@mickler.org, andi@firstfloor.org, mst@redhat.com, randy.dunlap@oracle.com Subject: Re: [PATCH 12/35] workqueue: update cwq alignement References: <1277759063-24607-1-git-send-email-tj@kernel.org> <1277759063-24607-13-git-send-email-tj@kernel.org> <20100628224755.GA10104@nowhere> <4C29A33D.2060407@kernel.org> <20100629123632.GB5318@nowhere> <4C2A145E.8030608@kernel.org> <20100629154738.GJ5318@nowhere> <4C2A1672.20700@kernel.org> <20100629160100.GL5318@nowhere> <4C2A1ABF.8050504@kernel.org> In-Reply-To: X-Enigmail-Version: 1.1.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Tue, 06 Jul 2010 14:26:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 857 Lines: 23 On 07/06/2010 04:22 PM, Christoph Lameter wrote: > On Tue, 29 Jun 2010, Tejun Heo wrote: > >> What alignment maintenance? Are you talking about the UP code? If >> you're talking about the UP code, the ugliness there is because the >> current UP __alloc_percpu() can't honor the alignment parameter. > > Why do we need alignment on UP? Cachelines typically dont bounce if a > single processor accesses the data. Because work->data is multiplexed with pointer and flag bits, so the targets of the pointer (cwq's) need to be aligned so that the lower part of the pointer always stays zero. Thanks. -- tejun -- 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/