Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760763Ab3EFXSn (ORCPT ); Mon, 6 May 2013 19:18:43 -0400 Received: from mail-wg0-f52.google.com ([74.125.82.52]:47759 "EHLO mail-wg0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757435Ab3EFXSk (ORCPT ); Mon, 6 May 2013 19:18:40 -0400 Date: Tue, 7 May 2013 01:18:37 +0200 From: Frederic Weisbecker To: Olivier Langlois Cc: Peter Zijlstra , Ingo Molnar , Thomas Gleixner , schwidefsky@de.ibm.com, Steven Rostedt , KOSAKI Motohiro , LKML Subject: Re: [PATCH v3 1/3] posix_timers: do not account group_exec_runtime for dying autoreaped tasks Message-ID: <20130506231835.GC1225@somewhere> References: <1367258649.8833.19.camel@Wailaba2> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1367258649.8833.19.camel@Wailaba2> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2316 Lines: 59 On Mon, Apr 29, 2013 at 02:04:09PM -0400, Olivier Langlois wrote: > > > Forbids the cputimer to drift ahead of its process clock by > blocking its update when a tick occurs while a autoreaping task > is currently in do_exit() between the call to release_task() and > its final call to schedule(). > > Any task stats update after having called release_task() will > be lost because they are added to the global process stats located > in the signal struct from release_task(). I wonder if this is real problem that the clock is ahead of the timer. Have you seen any issue in practice with this? Or may be it's a guarantee that the posix clock should provide wrt. to the timer? thanks. > > Signed-off-by: Olivier Langlois > --- > kernel/sched/fair.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 7a33e59..52d7b10 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -708,7 +708,15 @@ static void update_curr(struct cfs_rq *cfs_rq) > > trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime); > cpuacct_charge(curtask, delta_exec); > - account_group_exec_runtime(curtask, delta_exec); > + /* > + * Do not update the cputimer if the task is already released by > + * release_task(). > + * > + * it would preferable to defer the autoreap release_task > + * after the last context switch but harder to do. > + */ > + if (likely(curtask->sighand)) > + account_group_exec_runtime(curtask, delta_exec); > } > > account_cfs_rq_runtime(cfs_rq, delta_exec); > -- > 1.8.2.1 > > > -- > 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/ -- 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/