From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756094AbbI2PBA (ORCPT ); Tue, 29 Sep 2015 11:01:00 -0400 Received: from smtprelay0231.hostedemail.com ([216.40.44.231]:56669 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754154AbbI2PAx (ORCPT ); Tue, 29 Sep 2015 11:00:53 -0400 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::::,RULES_HIT:41:355:379:541:599:800:960:968:973:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:3138:3139:3140:3141:3142:3352:3865:3867:3868:3870:3871:3872:3874:5007:6261:7875:9010:10004:10400:10450:10455:10848:10967:11026:11232:11473:11658:11914:12296:12438:12517:12519:12663:12740:13069:13311:13357:14096:14097:19904:19999:21080,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0 X-HE-Tag: slip94_7bcde00a7a704 X-Filterd-Recvd-Size: 2268 Date: Tue, 29 Sep 2015 11:00:49 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, fweisbec@gmail.com, oleg@redhat.com, umgwanakikbuti@gmail.com, tglx@linutronix.de Subject: Re: [RFC][PATCH 01/11] sched: Simplify INIT_PREEMPT_COUNT Message-ID: <20150929110049.7b9de3eb@gandalf.local.home> In-Reply-To: <20150929143559.GL3816@twins.programming.kicks-ass.net> References: <20150929092825.540553633@infradead.org> <20150929093519.706413197@infradead.org> <20150929103729.00899e69@gandalf.local.home> <20150929143559.GL3816@twins.programming.kicks-ass.net> X-Mailer: Claws Mail 3.12.0 (GTK+ 2.24.28; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Resend, with the Cc list back ] On Tue, 29 Sep 2015 16:35:59 +0200 Peter Zijlstra wrote: > On Tue, Sep 29, 2015 at 10:37:29AM -0400, Steven Rostedt wrote: > > On Tue, 29 Sep 2015 11:28:26 +0200 > > Peter Zijlstra wrote: > > > > > As per commit d86ee4809d03 ("sched: optimize cond_resched()") we need > > > PREEMPT_ACTIVE to avoid cond_resched() from working before the > > > scheduler is setup. > > > > > > However, keeping preemption disabled should do the same thing already, > > > making the PREEMPT_ACTIVE part entirely redundant. > > > > Thus PREEMPT_ACTIVE wasn't needed at that commit either, or was it? > > Correct. We might have actually discussed that at that time but decided > to be conservative -- but these be vague memories.. Hmm, I just looked closer and I'm wondering if this still works? We have: #ifdef CONFIG_PREEMPT_COUNT #define PREEMPT_DISABLED (1 + PREEMPT_ENABLED) #else #define PREEMPT_DISABLED PREEMPT_ENABLED #endif Now if we just remove the PREEMPT_ACTIVE from the INIT_PREEMPT_COUNT, when CONFIG_PREEMPT_COUNT is not set, wouldn't a _cond_resched() in boot up schedule? -- Steve