Messages in this thread | | | Date | Fri, 23 Jan 2015 21:11:03 +0100 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH] sched, timer: Use atomics for thread_group_cputimer stats |
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On Fri, Jan 23, 2015 at 10:07:31AM -0800, Jason Low wrote: > On Fri, 2015-01-23 at 10:33 +0100, Peter Zijlstra wrote: > > > + .running = ATOMIC_INIT(0), \ > > > + atomic_t running; > > > + atomic_set(&sig->cputimer.running, 1); > > > @@ -174,7 +174,7 @@ static inline bool cputimer_running(struct task_struct *tsk) > > > + if (!atomic_read(&cputimer->running)) > > > + if (!atomic_read(&cputimer->running)) { > > > + atomic_set(&cputimer->running, 1); > > > + if (atomic_read(&tsk->signal->cputimer.running)) > > > + atomic_set(&cputimer->running, 0); > > > + if (atomic_read(&sig->cputimer.running)) { > > > + if (atomic_read(&tsk->signal->cputimer.running)) > > > > That doesn't really need an atomic_t. > > Yeah, I was wondering about that, and made it atomic since we had: > > raw_spin_lock_irqsave(&cputimer->lock, flags); > cputimer->running = 0; > raw_spin_unlock_irqrestore(&cputimer->lock, flags); > > in stop_process_timers().
Yeah, that could've been ACCESS_ONCE(cputimer->running) = 0. FWIW atomic_set() seems to not actually include the needed volatile cast.
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