From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: problems in linux-next (Was: Re: linux-next: Tree for December 1) Date: Thu, 03 Dec 2009 07:16:07 +0900 Message-ID: <4B16E727.9070104@kernel.org> References: <20091201190301.0fb7abad.sfr@canb.auug.org.au> <4B14D6E2.2040704@petalogix.com> <20091201210343.f0a1d353.sfr@canb.auug.org.au> <4B152D22.9070001@kernel.org> <20091201160119.GA10826@elte.hu> <4B15A5A6.2090200@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from hera.kernel.org ([140.211.167.34]:33502 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755682AbZLBWOv (ORCPT ); Wed, 2 Dec 2009 17:14:51 -0500 In-Reply-To: Sender: linux-next-owner@vger.kernel.org List-ID: To: Christoph Lameter Cc: Ingo Molnar , Stephen Rothwell , michal.simek@petalogix.com, linux-next@vger.kernel.org, LKML , Rusty Russell On 12/02/2009 11:55 PM, Christoph Lameter wrote: > On Wed, 2 Dec 2009, Tejun Heo wrote: > >> This isn't usual alignment. struct work_struct has one data fields >> which is overloaded for two purposes. Lower few bits are used to >> carry flags while upper bits are used to point to sruct >> cpu_workqueue_struct. So, the number of available bits for flags are >> determined by the alignment of cpu_workqueue_struct. Memory usage for > > The default mininum slab alignment in UP is 8 bytes which means you can > use 3 bits. And as far as I can see only the lower two bits are used. You > still have one bit leftover. (current upstream that is did not check if > you modified it). For colored workqueue flushing, it ends up using more than three bits. I haven't decided it fully yet but total of six or seven depending on how many colors are used. So, we need forced alignment anyway. Thanks. -- tejun