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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: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-02-10 16:37:31 +01:00 committed by Ingo Molnar
parent ff08f76d73
commit 3fccfd67df
2 changed files with 15 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/sched.h
View File

@ -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);
}

42
kernel/posix-cpu-timers.c
View File

@ -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) {