From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946042AbWGON60 (ORCPT ); Sat, 15 Jul 2006 09:58:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946048AbWGON60 (ORCPT ); Sat, 15 Jul 2006 09:58:26 -0400 Received: from viper.oldcity.dca.net ([216.158.38.4]:64957 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S1946042AbWGON6Z (ORCPT ); Sat, 15 Jul 2006 09:58:25 -0400 Subject: Re: Where is RLIMIT_RT_CPU? From: Lee Revell To: Jean-Marc Valin Cc: Esben Nielsen , linux-kernel@vger.kernel.org, Ingo Molnar In-Reply-To: <1152919240.6374.38.camel@idefix.homelinux.org> References: <1152663825.27958.5.camel@localhost> <1152809039.8237.48.camel@mindpipe> <1152869952.6374.8.camel@idefix.homelinux.org> <1152919240.6374.38.camel@idefix.homelinux.org> Content-Type: text/plain Date: Sat, 15 Jul 2006 09:58:15 -0400 Message-Id: <1152971896.16617.4.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2006-07-15 at 09:20 +1000, Jean-Marc Valin wrote: > > Can't you just make a prio 1 task which signals a prio 99 once say every > > second. If the priority 99 task doesn't get the signal after say 2 > > seconds, it will look for a rt task running wild. At worst it will have to do > > an O(n) algorith when things have gone wrong, not when everything is > > working. > > Well, that would work in sort of preventing a complete lockup, but the > watchdog wouldn't even know if the task eating lots of CPU is privileged > (OK) or unprivileged (not OK). Also, the original RLIMIT_RT_CPU feature > allowed you to really control how much CPU is available to unprivileged > users, not just prevent them from getting 100% CPU. Non-root RT tasks are not "unprivileged" - they have a level of privileges between a normal user and root. Really I think it's OK for these tasks to consume 100% CPU, as the admin has explicitly allowed it. The only problem is that Ubuntu shipped with this enabled for everyone. Lee