Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758052Ab0LTPxc (ORCPT ); Mon, 20 Dec 2010 10:53:32 -0500 Received: from canuck.infradead.org ([134.117.69.58]:57228 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757987Ab0LTPxb convert rfc822-to-8bit (ORCPT ); Mon, 20 Dec 2010 10:53:31 -0500 Subject: Re: [RFC PATCH 05/15] nohz_task: Restart the tick when another task compete on the cpu From: Peter Zijlstra To: Frederic Weisbecker Cc: LKML , Thomas Gleixner , "Paul E. McKenney" , Ingo Molnar , Steven Rostedt , Lai Jiangshan , Andrew Morton , Anton Blanchard , Tim Pepper In-Reply-To: <1292858662-5650-6-git-send-email-fweisbec@gmail.com> References: <1292858662-5650-1-git-send-email-fweisbec@gmail.com> <1292858662-5650-6-git-send-email-fweisbec@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Mon, 20 Dec 2010 16:53:21 +0100 Message-ID: <1292860401.5021.9.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 957 Lines: 22 On Mon, 2010-12-20 at 16:24 +0100, Frederic Weisbecker wrote: > +#ifdef CONFIG_NO_HZ_TASK > + /* > + * CHECKME: > + * Ideally, we need to check if the target has a nohz task > + * and only send the IPI if so. But there is nothing but > + * a racy way to do that. Or can we assume at that point > + * of the wake up that if cpu_has_nohz_task(cpu) is 0, then > + * it's ok, even if it has a task about to switch to nohz > + * task mode? > + */ > + if (rq->nr_running == 2) > + smp_send_update_nohz_task_cpu(cpu); > +#endif This is the wrong place, use ttwu_activate(), since activate_task() is the thing that pokes at nr_running. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/