From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751727AbcASFOu (ORCPT ); Tue, 19 Jan 2016 00:14:50 -0500 Received: from mail-wm0-f52.google.com ([74.125.82.52]:33635 "EHLO mail-wm0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751014AbcASFOq (ORCPT ); Tue, 19 Jan 2016 00:14:46 -0500 Message-ID: <1453180483.3516.1.camel@gmail.com> Subject: Re: [rfc patch v4.4-rt2] sched: fix up preempt lazy forward port From: Mike Galbraith To: Sebastian Andrzej Siewior Cc: Thomas Gleixner , LKML , linux-rt-users Date: Tue, 19 Jan 2016 06:14:43 +0100 In-Reply-To: <1453178516.4217.2.camel@gmail.com> References: <1453108103.4123.4.camel@gmail.com> <20160118201828.GE12309@linutronix.de> <1453178516.4217.2.camel@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2016-01-19 at 05:41 +0100, Mike Galbraith wrote: > On Mon, 2016-01-18 at 21:18 +0100, Sebastian Andrzej Siewior wrote: > > > > --- a/kernel/sched/core.c > > > +++ b/kernel/sched/core.c > > > @@ -3542,6 +3542,15 @@ asmlinkage __visible void __sched notrac > > > if (likely(!preemptible())) > > > return; > > > > > > +#ifdef CONFIG_PREEMPT_LAZY > > > + /* > > > + * Check for lazy preemption > > > + */ > > > + if (current_thread_info()->preempt_lazy_count && > > > + !test_thread_flag(TIF_NEED_RESCHED)) > > > + return; > > > +#endif > > > + > > > > And this is a new piece. So you forbid that tasks leave the CPU if > > lazy_count > 0. Let me look closed why this is happening and if > > this is > > v4.1 … v4.4 or not. > > That check wants a !rt_task(current) qualifier anyway. (bah, -ESWILLMORECOFFEE)