From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751081AbWCDF16 (ORCPT ); Sat, 4 Mar 2006 00:27:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751082AbWCDF16 (ORCPT ); Sat, 4 Mar 2006 00:27:58 -0500 Received: from mail.gmx.net ([213.165.64.20]:36255 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S1751081AbWCDF15 (ORCPT ); Sat, 4 Mar 2006 00:27:57 -0500 X-Authenticated: #14349625 Subject: Re: [patch 2.6.16-rc5-mm2] sched_cleanup-V17 - task throttling patch 1 of 2 From: Mike Galbraith To: Con Kolivas Cc: Peter Williams , lkml , mingo@elte.hu, nickpiggin@yahoo.com.au, "Chen, Kenneth W" , Andrew Morton In-Reply-To: <200603041624.06656.kernel@kolivas.org> References: <1140183903.14128.77.camel@homer> <4408FC8B.4050802@bigpond.net.au> <1141449654.7703.36.camel@homer> <200603041624.06656.kernel@kolivas.org> Content-Type: text/plain Date: Sat, 04 Mar 2006 06:29:47 +0100 Message-Id: <1141450187.7703.40.camel@homer> Mime-Version: 1.0 X-Mailer: Evolution 2.4.0 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2006-03-04 at 16:24 +1100, Con Kolivas wrote: > On Saturday 04 March 2006 16:20, Mike Galbraith wrote: > > On Sat, 2006-03-04 at 13:33 +1100, Peter Williams wrote: > > > > include/linux/sched.h | 3 - > > > > kernel/sched.c | 136 > > > > +++++++++++++++++++++++++++++--------------------- 2 files changed, 82 > > > > insertions(+), 57 deletions(-) > > > > > > > > --- linux-2.6.16-rc5-mm2/include/linux/sched.h.org 2006-03-01 > > > > 15:06:22.000000000 +0100 +++ > > > > linux-2.6.16-rc5-mm2/include/linux/sched.h 2006-03-02 > > > > 08:33:12.000000000 +0100 @@ -720,7 +720,8 @@ > > > > > > > > unsigned long policy; > > > > cpumask_t cpus_allowed; > > > > - unsigned int time_slice, first_time_slice; > > > > + int time_slice; > > > > > > Can you guarantee that int is big enough to hold a time slice in > > > nanoseconds on all systems? I think that you'll need more than 16 bits. > > > > Nope, that's a big fat bug. > > Most ints are 32bit anyway, but even a 32 bit unsigned int overflows with > nanoseconds at 4.2 seconds. A signed one at about half that. Our timeslices > are never that large, but then int isn't always 32bit either. Yup. I just didn't realize that there were 16 bit integers out there. -Mike