Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762286Ab3ECEti (ORCPT ); Fri, 3 May 2013 00:49:38 -0400 Received: from mail-qe0-f50.google.com ([209.85.128.50]:39244 "EHLO mail-qe0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759622Ab3ECEtc (ORCPT ); Fri, 3 May 2013 00:49:32 -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 4/7] posix-cpu-timers: timer functions should use timer time instead of clock time Date: Fri, 3 May 2013 00:47:45 -0400 Message-Id: <1367556468-4021-6-git-send-email-kosaki.motohiro@gmail.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1367556468-4021-1-git-send-email-kosaki.motohiro@gmail.com> References: <1367556468-4021-1-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: 4540 Lines: 127 From: KOSAKI Motohiro For process timers, we use cpu_clock_sample_group() and cpu_timer_sample_group() correctly. However, for thread timers, we always use cpu_clock_sample(). This is wrong because a cpu_clock_sample() accounts uncommitted delta_exec too. And this is inconsistent against run_posix_cpu_tiemrs(). This is not big matter because the following workaround code in posix_cpu_timer_get() hides the timer miscalculation issue. However, it makes rq lock held wrongly and it would be better to fix it. if (cpu_time_before(timer->it_clock, now, timer->it.cpu.expires)) { ... } else { /* * The timer should have expired already, but the firing * hasn't taken place yet. Say it's just about to expire. */ itp->it_value.tv_nsec = 1; itp->it_value.tv_sec = 0; Cc: Olivier Langlois Cc: Thomas Gleixner Cc: Frederic Weisbecker Cc: Ingo Molnar Acked-by: Peter Zijlstra Signed-off-by: KOSAKI Motohiro --- kernel/posix-cpu-timers.c | 37 +++++++++++++++++++++++++++---------- 1 files changed, 27 insertions(+), 10 deletions(-) diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c index 98f354e..c69b8d8 100644 --- a/kernel/posix-cpu-timers.c +++ b/kernel/posix-cpu-timers.c @@ -204,11 +204,10 @@ posix_cpu_clock_set(const clockid_t which_clock, const struct timespec *tp) } -/* - * Sample a per-thread clock for the given task. - */ -static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p, - union cpu_time_count *cpu) +static int do_cpu_clock_timer_sample(const clockid_t which_clock, + struct task_struct *p, + bool add_delta, + union cpu_time_count *cpu) { switch (CPUCLOCK_WHICH(which_clock)) { default: @@ -220,12 +219,30 @@ static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p, cpu->cpu = virt_ticks(p); break; case CPUCLOCK_SCHED: - cpu->sched = task_sched_runtime(p, true); + cpu->sched = task_sched_runtime(p, add_delta); break; } return 0; } +/* + * Sample a per-thread clock for the given task. + */ +static int cpu_clock_sample(const clockid_t which_clock, struct task_struct *p, + union cpu_time_count *cpu) +{ + return do_cpu_clock_timer_sample(which_clock, p, true, cpu); +} + +/* + * Sample a per-thread timer clock for the given task. + */ +static int cpu_timer_sample(const clockid_t which_clock, struct task_struct *p, + union cpu_time_count *cpu) +{ + return do_cpu_clock_timer_sample(which_clock, p, false, cpu); +} + static void update_gt_cputime(struct task_cputime *a, struct task_cputime *b) { if (b->utime > a->utime) @@ -700,7 +717,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int flags, * check if it's already passed. In short, we need a sample. */ if (CPUCLOCK_PERTHREAD(timer->it_clock)) { - cpu_clock_sample(timer->it_clock, p, &val); + cpu_timer_sample(timer->it_clock, p, &val); } else { cpu_timer_sample_group(timer->it_clock, p, &val); } @@ -756,7 +773,7 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int flags, * we need exact current time. */ if (CPUCLOCK_PERTHREAD(timer->it_clock)) - now = val; + cpu_clock_sample(timer->it_clock, p, &now); else cpu_clock_sample_group(timer->it_clock, p, &now); cpu_time_add(timer->it_clock, &new_expires, now); @@ -844,7 +861,7 @@ static void posix_cpu_timer_get(struct k_itimer *timer, struct itimerspec *itp) * Sample the clock to take the difference with the expiry time. */ if (CPUCLOCK_PERTHREAD(timer->it_clock)) { - cpu_clock_sample(timer->it_clock, p, &now); + cpu_timer_sample(timer->it_clock, p, &now); clear_dead = p->exit_state; } else { read_lock(&tasklist_lock); @@ -1168,7 +1185,7 @@ void posix_cpu_timer_schedule(struct k_itimer *timer) * Fetch the current sample and update the timer's expiry time. */ if (CPUCLOCK_PERTHREAD(timer->it_clock)) { - cpu_clock_sample(timer->it_clock, p, &now); + cpu_timer_sample(timer->it_clock, p, &now); bump_cpu_timer(timer, now); if (unlikely(p->exit_state)) { clear_dead_task(timer, now); -- 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/