From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753399Ab1IWLTO (ORCPT ); Fri, 23 Sep 2011 07:19:14 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123]:38905 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753170Ab1IWLTM (ORCPT ); Fri, 23 Sep 2011 07:19:12 -0400 X-Authority-Analysis: v=1.1 cv=agqPq5NoKwAPC9P66H7dbYUCjxvmT73as08i4x3aqAA= c=1 sm=0 a=pPwHPQqvJkcA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=17wjrS5wAhQaEczCPkpxpQ==:17 a=meVymXHHAAAA:8 a=VwQbUJbxAAAA:8 a=NKZoUttrmXKZofYut5QA:9 a=PUjeQqilurYA:10 a=U62fhAwekXMA:10 a=jeBq3FmKZ4MA:10 a=17wjrS5wAhQaEczCPkpxpQ==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.83.30 Subject: Re: [PATCH 19/21] tracing: Account for preempt off in preempt_schedule() From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Frederic Weisbecker , Thomas Gleixner In-Reply-To: <1316775648.9084.1.camel@twins> References: <20110922220935.537134016@goodmis.org> <20110922221029.678324653@goodmis.org> <1316775648.9084.1.camel@twins> Content-Type: text/plain; charset="ISO-8859-15" Date: Fri, 23 Sep 2011 07:19:09 -0400 Message-ID: <1316776749.29966.156.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.32.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2011-09-23 at 13:00 +0200, Peter Zijlstra wrote: > > > Signed-off-by: Steven Rostedt > > --- > > kernel/sched.c | 9 +++++++++ > > 1 files changed, 9 insertions(+), 0 deletions(-) > > > > diff --git a/kernel/sched.c b/kernel/sched.c > > index ccacdbd..4b096cc 100644 > > --- a/kernel/sched.c > > +++ b/kernel/sched.c > > @@ -4435,7 +4435,16 @@ asmlinkage void __sched notrace preempt_schedule(void) > > > > do { > > add_preempt_count_notrace(PREEMPT_ACTIVE); > > + /* > > + * The add/subtract must not be traced by the function > > + * tracer. But we still want to account for the > > + * preempt off latency tracer. Since the _notrace versions > > + * of add/subtract skip the accounting for latency tracer > > + * we must force it manually. > > + */ > > + start_critical_timings(); > > schedule(); > > + stop_critical_timings(); > > sub_preempt_count_notrace(PREEMPT_ACTIVE); > > > > /* > > This won't apply, you're patching ancient code. Yes, that's the way git usually works. I could start a new branch for this. But since we are not doing many pulls while kernel.org is down, my kernel base has become a bit out of date. I thought that's the way Linus wants it. I'm sure this would apply with a trivial merge fixup. But if you want to take this patch, then I could rebase my tree and take it out. > > Anyway, this all stinks, and reading the changelog of > d1f74e20b5b064a130cd0743a256c2d3cfe84010 and the above just makes me > confused. > What would you suggest? Just ignore the latencies that schedule produces, even though its been one of the top causes of latencies? -- Steve