Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262254AbVBBLh5 (ORCPT ); Wed, 2 Feb 2005 06:37:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262289AbVBBLh5 (ORCPT ); Wed, 2 Feb 2005 06:37:57 -0500 Received: from mx1.elte.hu ([157.181.1.137]:59570 "EHLO mx1.elte.hu") by vger.kernel.org with ESMTP id S262254AbVBBLhp (ORCPT ); Wed, 2 Feb 2005 06:37:45 -0500 Date: Wed, 2 Feb 2005 12:37:05 +0100 From: Ingo Molnar To: "Jack O'Quin" Cc: Nick Piggin , Paul Davis , Con Kolivas , linux , rlrevell@joe-job.com, CK Kernel , utz , Andrew Morton , alexn@dsv.su.se, Rui Nuno Capela , Chris Wright , Arjan van de Ven Subject: Re: [patch, 2.6.11-rc2] sched: RLIMIT_RT_CPU_RATIO feature Message-ID: <20050202113705.GA25012@elte.hu> References: <20050125135613.GA18650@elte.hu> <87sm4opxto.fsf@sulphur.joq.us> <20050126070404.GA27280@elte.hu> <87fz0neshg.fsf@sulphur.joq.us> <1106782165.5158.15.camel@npiggin-nld.site> <874qh3bo1u.fsf@sulphur.joq.us> <1106796360.5158.39.camel@npiggin-nld.site> <87pszr1mi1.fsf@sulphur.joq.us> <20050127113530.GA30422@elte.hu> <873bwfo8br.fsf@sulphur.joq.us> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <873bwfo8br.fsf@sulphur.joq.us> User-Agent: Mutt/1.4.1i X-ELTE-SpamVersion: MailScanner 4.31.6-itk1 (ELTE 1.2) SpamAssassin 2.63 ClamAV 0.73 X-ELTE-VirusStatus: clean X-ELTE-SpamCheck: no X-ELTE-SpamCheck-Details: score=-4.9, required 5.9, autolearn=not spam, BAYES_00 -4.90 X-ELTE-SpamLevel: X-ELTE-SpamScore: -4 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1446 Lines: 37 * Jack O'Quin wrote: > Remember when I asked how you handle changes to sizeof(struct rusage)? > That was a serious question. I hope there's a solution. [...] what does any of what we've talking about have to do with struct rusage? One of the patches i wrote adds a new rlimit. It has no impact on rusage, at all. A new rlimit can be added transparently, we routinely add new rlimits, and no, most of them have no matching rusage fields! > But, I got no answer, only handwaving. i very much replied to your point: http://marc.theaimsgroup.com/?l=linux-kernel&m=110672338910363&w=2 " > Does getrusage() return anything for this? How can a field be added > to the rusage struct without breaking binary compatibility? Can we > assume that no programs ever use sizeof(struct rusage)? rlimits are easily extended and there are no binary compatibility worries. The kernel doesnt export the maximum towards userspace. getrusage() will return the value on new kernels and will return -EINVAL on old kernels, so new userspace can deal with this accordingly. " (and here i meant getrlimit(), not getrusage() - getrusage() is not affected by the patch at all.) Ingo - 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/