Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967708AbXEHDbK (ORCPT ); Mon, 7 May 2007 23:31:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S967674AbXEHDbG (ORCPT ); Mon, 7 May 2007 23:31:06 -0400 Received: from fgwmail6.fujitsu.co.jp ([192.51.44.36]:32904 "EHLO fgwmail6.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967672AbXEHDbF (ORCPT ); Mon, 7 May 2007 23:31:05 -0400 Date: Tue, 08 May 2007 12:29:19 +0900 Message-ID: <874pmoro1c.wl%takeuchi_satoru@jp.fujitsu.com> From: Satoru Takeuchi To: Rusty Russell Cc: Satoru Takeuchi , Linux Kernel , Srivatsa Vaddagiri , Zwane Mwaikambo , Nathan Lynch , Joel Schopp , Ashok Raj , Heiko Carstens , Gautham R Shenoy Subject: Re: [BUG] cpu-hotplug: Can't offline the CPU with naughty realtime processes In-Reply-To: <1178593345.28438.29.camel@localhost.localdomain> References: <87bqgxrlky.wl%takeuchi_satoru@jp.fujitsu.com> <1178545373.28438.7.camel@localhost.localdomain> <877irkrq8a.wl%takeuchi_satoru@jp.fujitsu.com> <1178593345.28438.29.camel@localhost.localdomain> User-Agent: Wanderlust/2.14.0 (Africa) SEMI/1.14.6 (Maruoka) FLIM/1.14.8 (=?ISO-8859-4?Q?Shij=F2?=) APEL/10.6 Emacs/21.4 (i486-pc-linux-gnu) MULE/5.0 (SAKAKI) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1307 Lines: 36 At Tue, 08 May 2007 13:02:25 +1000, Rusty Russell wrote: > > On Tue, 2007-05-08 at 11:41 +0900, Satoru Takeuchi wrote: > > At Mon, 07 May 2007 23:42:53 +1000, > > Rusty Russell wrote: > > > I look forward to your patch! > > > Rusty. > > > > Thanks, I'll do. Maybe this work will take several days including test. > > Excellent. > > > BTW, how should I manage rt process having max priority as Gautham said? > > He said that it's OK unless such kernel thread exists. However, currently > > MAX_USER_RT_PRIORITY is equal to MAX_RT_PRIO, so user process also be able > > to cause this problem. Is Srivatsa's idea 2 acceptable? Or just apply > > "Shouldn't abuse highest rt proority" rule? > > We used to be able to create kernel threads higher than any userspace > priority. If this is no longer true, I think that's OK: equal priority > still means we'll get scheduled, right? IF SCHED_RR, yes. However, if SCHED_FIFO, no. Such process doen't have timeslice and only relinquish CPU time voluntarily. # Hence this problem is complicated ;-( Thanks, Satoru - 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/