Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262461AbVA0AIt (ORCPT ); Wed, 26 Jan 2005 19:08:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262529AbVA0AIM (ORCPT ); Wed, 26 Jan 2005 19:08:12 -0500 Received: from gizmo05ps.bigpond.com ([144.140.71.40]:60579 "HELO gizmo05ps.bigpond.com") by vger.kernel.org with SMTP id S262461AbVAZVoh (ORCPT ); Wed, 26 Jan 2005 16:44:37 -0500 Message-ID: <41F80F41.5040106@bigpond.net.au> Date: Thu, 27 Jan 2005 08:44:33 +1100 From: Peter Williams User-Agent: Mozilla Thunderbird 0.9 (X11/20041127) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Ingo Molnar CC: "Jack O'Quin" , 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 , Nick Piggin Subject: Re: [patch, 2.6.11-rc2] sched: RLIMIT_RT_CPU feature, -D7 References: <87y8eo9hed.fsf@sulphur.joq.us> <20050120172506.GA20295@elte.hu> <87wtu6fho8.fsf@sulphur.joq.us> <20050122165458.GA14426@elte.hu> <87hdl940ph.fsf@sulphur.joq.us> <20050124085902.GA8059@elte.hu> <20050124125814.GA31471@elte.hu> <20050125135613.GA18650@elte.hu> <41F6C5CE.9050303@bigpond.net.au> <41F6C797.80403@bigpond.net.au> <20050126100846.GB8720@elte.hu> In-Reply-To: <20050126100846.GB8720@elte.hu> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1424 Lines: 37 Ingo Molnar wrote: > * Peter Williams wrote: > > >>Oops, after rereading the patch, a task that set its RT_CPU_RATIO >>rlimit to zero wouldn't be escaping the mechanism at all. It would be >>suffering maximum throttling. [...] > > > my intention was to let 'limit 0' mean 'old RT semantics' - i.e. 'no RT > CPU time for unprivileged tasks at all', and only privileged tasks may > do it and then they'll get full CPU time with no throttling. > > so in that context your observation highlights another bug, which i > fixed in the -D7 patch available from the usual place: > > http://redhat.com/~mingo/rt-limit-patches/ > > not doing the '0' exception would make it harder to introduce the rlimit > in a compatible fashion. (My current thinking is that the default RT_CPU > rlimit should be 0.) One solution to this dilemma might be to set a PF_FLAG on a task whenever it gains RT status via this privilege bypass and only apply the limit to tasks that have that flag set. Peter -- Peter Williams pwil3058@bigpond.net.au "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce - 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/