From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from digeo-nav01.digeo.com (digeo-nav01.digeo.com [192.168.1.233]) by packet.digeo.com (8.9.3+Sun/8.9.3) with SMTP id PAA06441 for ; Sun, 6 Oct 2002 15:33:27 -0700 (PDT) Message-ID: <3DA0BA33.5B295A46@digeo.com> Date: Sun, 06 Oct 2002 15:33:23 -0700 From: Andrew Morton MIME-Version: 1.0 Subject: Re: 2.5.40-mm2 References: <3DA0B422.C23B23D4@digeo.com> <1033943021.27093.29.camel@phantasy> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Robert Love Cc: Dave Hansen , lkml , "linux-mm@kvack.org" , Ingo Molnar List-ID: Robert Love wrote: > > On Sun, 2002-10-06 at 18:07, Andrew Morton wrote: > > > > - while (base->running_timer == timer) { > > > + while (base->running_timer == timer) > > > cpu_relax(); > > > - preempt_disable(); > > > - preempt_enable(); > > I am confused as to why Ingo would put these here. He knows very well > what he is doing... surely he had a reason. > > If he intended to force a preemption point here, then the lines needs to > be reversed. This assumes, of course, preemption is disabled here. But > I do not think it is. > > If he just wanted to check for preemption, we have a > preempt_check_resched() which does just that (I even think he wrote > it). Note as long as interrupts are enabled this probably does not > achieve much anyhow. > I think it's a way of doing "cond_resched() if cond_resched() is a legal thing to do right now". I'm sure David isn't using preempt though. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/