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Commit 3fccfd67 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

timers: split process wide cpu clocks/timers, fix 



To decrease the chance of a missed enable, always enable the timer when we
sample it, we'll always disable it when we find that there are no active timers
in the jiffy tick.

This fixes a flood of warnings reported by Mike Galbraith.

Reported-by: default avatarMike Galbraith <efault@gmx.de>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ff08f76d

include/linux/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -2209,6 +2209,7 @@ void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times) 
	unsigned long flags;



	spin_lock_irqsave(&cputimer->lock, flags);

	cputimer->running = 1;

	*times = cputimer->cputime;

	spin_unlock_irqrestore(&cputimer->lock, flags);

}

kernel/posix-cpu-timers.c

+14 −28
Original line number Diff line number Diff line
@@ -488,7 +488,7 @@ void posix_cpu_timers_exit_group(struct task_struct *tsk) 
{

	struct task_cputime cputime;



	thread_group_cputime(tsk, &cputime);

	thread_group_cputimer(tsk, &cputime);

	cleanup_timers(tsk->signal->cpu_timers,

		       cputime.utime, cputime.stime, cputime.sum_exec_runtime);

}
@@ -506,29 +506,6 @@ static void clear_dead_task(struct k_itimer *timer, union cpu_time_count now) 
					     now);

}



/*

 * Enable the process wide cpu timer accounting.

 *

 * serialized using ->sighand->siglock

 */

static void start_process_timers(struct task_struct *tsk)

{

	tsk->signal->cputimer.running = 1;

	barrier();

}



/*

 * Release the process wide timer accounting -- timer stops ticking when

 * nobody cares about it.

 *

 * serialized using ->sighand->siglock

 */

static void stop_process_timers(struct task_struct *tsk)

{

	tsk->signal->cputimer.running = 0;

	barrier();

}



/*

 * Insert the timer on the appropriate list before any timers that

 * expire later.  This must be called with the tasklist_lock held
@@ -549,9 +526,6 @@ static void arm_timer(struct k_itimer *timer, union cpu_time_count now) 
	BUG_ON(!irqs_disabled());

	spin_lock(&p->sighand->siglock);



	if (!CPUCLOCK_PERTHREAD(timer->it_clock))

		start_process_timers(p);



	listpos = head;

	if (CPUCLOCK_WHICH(timer->it_clock) == CPUCLOCK_SCHED) {

		list_for_each_entry(next, head, entry) {
@@ -1021,6 +995,19 @@ static void check_thread_timers(struct task_struct *tsk, 
	}

}



static void stop_process_timers(struct task_struct *tsk)

{

	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;

	unsigned long flags;



	if (!cputimer->running)

		return;



	spin_lock_irqsave(&cputimer->lock, flags);

	cputimer->running = 0;

	spin_unlock_irqrestore(&cputimer->lock, flags);

}



/*

 * 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
@@ -1427,7 +1414,6 @@ void set_process_cpu_timer(struct task_struct *tsk, unsigned int clock_idx, 
	struct list_head *head;



	BUG_ON(clock_idx == CPUCLOCK_SCHED);

	start_process_timers(tsk);

	cpu_timer_sample_group(clock_idx, tsk, &now);



	if (oldval) {