Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030880Ab3DSOwK (ORCPT ); Fri, 19 Apr 2013 10:52:10 -0400 Received: from mail-we0-f170.google.com ([74.125.82.170]:60579 "EHLO mail-we0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030702Ab3DSOvw (ORCPT ); Fri, 19 Apr 2013 10:51:52 -0400 From: Frederic Weisbecker To: Ingo Molnar Cc: LKML , Frederic Weisbecker , Chris Metcalf , Christoph Lameter , Geoff Levand , Gilad Ben Yossef , Hakan Akkan , Kevin Hilman , Li Zhong , Oleg Nesterov , "Paul E. McKenney" , Paul Gortmaker , Peter Zijlstra , Steven Rostedt , Thomas Gleixner Subject: [PATCH 3/3] posix_timers: New API to prevent from stopping the tick when timers are running Date: Fri, 19 Apr 2013 16:51:40 +0200 Message-Id: <1366383100-17053-4-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 In-Reply-To: <1366383100-17053-1-git-send-email-fweisbec@gmail.com> References: <1366383100-17053-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3611 Lines: 111 Bring a new helper that the full dynticks infrastructure can call in order to know if it can safely stop the tick from the posix cpu timers subsystem point of view. Signed-off-by: Frederic Weisbecker Cc: Chris Metcalf Cc: Christoph Lameter Cc: Geoff Levand Cc: Gilad Ben Yossef Cc: Hakan Akkan Cc: Ingo Molnar Cc: Kevin Hilman Cc: Li Zhong Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Paul Gortmaker Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner --- include/linux/posix-timers.h | 2 ++ kernel/posix-cpu-timers.c | 41 ++++++++++++++++++++++++++--------------- 2 files changed, 28 insertions(+), 15 deletions(-) diff --git a/include/linux/posix-timers.h b/include/linux/posix-timers.h index 042058f..3698d9d 100644 --- a/include/linux/posix-timers.h +++ b/include/linux/posix-timers.h @@ -122,6 +122,8 @@ void run_posix_cpu_timers(struct task_struct *task); void posix_cpu_timers_exit(struct task_struct *task); void posix_cpu_timers_exit_group(struct task_struct *task); +bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk); + void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx, cputime_t *newval, cputime_t *oldval); diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index 0bc3356..84d5cb3 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -155,6 +155,21 @@ static void bump_cpu_timer(struct k_itimer *timer, } } +/** + * task_cputime_zero - Check a task_cputime struct for all zero fields. + * + * @cputime: The struct to compare. + * + * Checks @cputime to see if all fields are zero. Returns true if all fields + * are zero, false if any field is nonzero. + */ +static inline int task_cputime_zero(const struct task_cputime *cputime) +{ + if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime) + return 1; + return 0; +} + static inline cputime_t prof_ticks(struct task_struct *p) { cputime_t utime, stime; @@ -654,6 +669,17 @@ static void posix_cpu_timer_kick_nohz(void) { schedule_work(&nohz_kick_work); } + +bool posix_cpu_timers_can_stop_tick(struct task_struct *tsk) +{ + if (!task_cputime_zero(&tsk->cputime_expires)) + return true; + + if (tsk->signal->cputimer.running) + return true; + + return false; +} #else static inline void posix_cpu_timer_kick_nohz(void) { } #endif @@ -1032,21 +1058,6 @@ static void check_cpu_itimer(struct task_struct *tsk, struct cpu_itimer *it, } } -/** - * task_cputime_zero - Check a task_cputime struct for all zero fields. - * - * @cputime: The struct to compare. - * - * Checks @cputime to see if all fields are zero. Returns true if all fields - * are zero, false if any field is nonzero. - */ -static inline int task_cputime_zero(const struct task_cputime *cputime) -{ - if (!cputime->utime && !cputime->stime && !cputime->sum_exec_runtime) - return 1; - return 0; -} - /* * Check for any per-thread CPU timers that have fired and move them * off the tsk->*_timers list onto the firing list. Per-thread timers -- 1.7.5.4 -- 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/