Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755297Ab3EZVgP (ORCPT ); Sun, 26 May 2013 17:36:15 -0400 Received: from mail-vb0-f52.google.com ([209.85.212.52]:44346 "EHLO mail-vb0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755224Ab3EZVgK (ORCPT ); Sun, 26 May 2013 17:36:10 -0400 From: kosaki.motohiro@gmail.com To: linux-kernel@vger.kernel.org Cc: Olivier Langlois , Thomas Gleixner , Frederic Weisbecker , Ingo Molnar , Peter Zijlstra , KOSAKI Motohiro Subject: [PATCH 1/8] posix-cpu-timers: don't account cpu timer after stopped thread runtime accounting Date: Sun, 26 May 2013 17:35:41 -0400 Message-Id: <1369604149-13016-3-git-send-email-kosaki.motohiro@gmail.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1369604149-13016-1-git-send-email-kosaki.motohiro@gmail.com> References: <1369604149-13016-1-git-send-email-kosaki.motohiro@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3112 Lines: 95 From: KOSAKI Motohiro When tsk->signal->cputimer->running is 1, signal->cputimer (i.e. per process timer account) and tsk->sum_sched_runtime (i.e. per thread timer account) increase at the same pace because update_curr() increases both accounting. However, there is one exception. When thread exiting, __exit_signal() turns over task's sum_shced_runtime to sig->sum_sched_runtime, but it doesn't stop signal->cputimer accounting. This inconsistency makes POSIX timer wake up too early. This patch fixes it. Cc: Thomas Gleixner Cc: Ingo Molnar Acked-by: Frederic Weisbecker Acked-by: Peter Zijlstra Signed-off-by: Olivier Langlois Signed-off-by: KOSAKI Motohiro --- kernel/sched/stats.h | 33 ++++++++++++++++++++++++++++++--- 1 files changed, 30 insertions(+), 3 deletions(-) diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h index 2ef90a5..8a0567f 100644 --- a/kernel/sched/stats.h +++ b/kernel/sched/stats.h @@ -162,6 +162,33 @@ sched_info_switch(struct task_struct *prev, struct task_struct *next) */ /** + * cputimer_running - return true if cputimer is running + * + * @tsk: Pointer to target task. + */ +static inline bool cputimer_running(struct task_struct *tsk) + +{ + struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; + + if (!cputimer->running) + return false; + + /* + * After turning over se.sum_exec_runtime's time accounting to + * sig->sum_sched_runtime in __exit_signal(), a per-thread cputime + * of the thread is going to be lost. We must not account exec_runtime + * here too because we need to keep consistent cputime between + * per-thread and per-process. Otherwise, the inconsistency is + * observable when single thread program run. + */ + if (unlikely(!tsk->sighand)) + return false; + + return true; +} + +/** * account_group_user_time - Maintain utime for a thread group. * * @tsk: Pointer to task structure. @@ -176,7 +203,7 @@ static inline void account_group_user_time(struct task_struct *tsk, { struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; - if (!cputimer->running) + if (!cputimer_running(tsk)) return; raw_spin_lock(&cputimer->lock); @@ -199,7 +226,7 @@ static inline void account_group_system_time(struct task_struct *tsk, { struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; - if (!cputimer->running) + if (!cputimer_running(tsk)) return; raw_spin_lock(&cputimer->lock); @@ -222,7 +249,7 @@ static inline void account_group_exec_runtime(struct task_struct *tsk, { struct thread_group_cputimer *cputimer = &tsk->signal->cputimer; - if (!cputimer->running) + if (!cputimer_running(tsk)) return; raw_spin_lock(&cputimer->lock); -- 1.7.1 -- 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/