From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754629AbYJAJIg (ORCPT ); Wed, 1 Oct 2008 05:08:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751963AbYJAJI2 (ORCPT ); Wed, 1 Oct 2008 05:08:28 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:52157 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751215AbYJAJI1 (ORCPT ); Wed, 1 Oct 2008 05:08:27 -0400 Date: Wed, 1 Oct 2008 11:08:09 +0200 From: Ingo Molnar To: Mike Travis Cc: Rusty Russell , Linus Torvalds , Andrew Morton , David Miller , Yinghai Lu , Thomas Gleixner , Jack Steiner , linux-kernel@vger.kernel.org Subject: Re: [PATCH 05/31] cpumask: Provide new cpumask API Message-ID: <20081001090809.GA8281@elte.hu> References: <20080929180250.111209000@polaris-admin.engr.sgi.com> <20080929180250.825653000@polaris-admin.engr.sgi.com> <20080930091140.GB27452@elte.hu> <48E248CB.5080305@sgi.com> <48E25111.7060305@sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48E25111.7060305@sgi.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Mike Travis wrote: > Mike Travis wrote: > > Ingo Molnar wrote: > ... > > > >> In what way will Rusty's changes differ? Since you incorporate some of > >> Rusty's changes already, could you please iterate towards a single > >> patchset which we could then start testing? > > > > Our timezones are not very conducive to a lot of email exchanges > > (and he's moving.) From what I've seen I believe he's leaning > > towards using struct cpumask * and less trickery than I have. actually, that's quite sane to do. const_cpumask_t looked a bit weird to me. the extra indirection to a cpumask_t is not a big issue IMO, so in that sense whether we pass by value or pass by reference is not a _big_ performance item. The complications (both present and expected ones) all come from the allocations. > Oh yeah, I forgot the other major point of Rusty's approach. He wants > the patchset to be completely bisectable. That's far from true in my > version. well, it should be a smooth transition and completely bisectable, there's hundreds of usages of cpumask_t and quite many in the pipeline. It's far easier to _you_ to get this stuff to work if it's all gradual and is expected to work all across. Have a default-off debug mode that turns off compatible cpumask_t perhaps - we can remove that later on. with 'struct cpumask' we could keep cpumask_t as the compatible API, and could see the impact of these changes in a very finegrained and gradual way. Seems like a fundamentally sane approach to me ... Ingo