On 29-03-17, 23:28, Rafael J. Wysocki wrote:
> On Thursday, March 09, 2017 05:15:15 PM Viresh Kumar wrote:
> > @@ -216,7 +216,7 @@ static void sugov_update_single(struct update_util_data
> > *hook, u64 time,
> > if (flags & SCHED_CPUFREQ_RT_DL) {
> > next_f = policy->cpuinfo.max_freq;
> > } else {
> > - sugov_get_util(&util, &max);
> > + sugov_get_util(&util, &max, hook->cpu);
>
> Why is this not racy?
Why would reading the utilization values be racy? The only dynamic value here is
"util_avg" and I am not sure if reading it is racy.
But, this whole routine has races which I ignored as we may end up updating
frequency simultaneously from two threads.
> > sugov_iowait_boost(sg_cpu, &util, &max);
> > next_f = get_next_freq(sg_policy, util, max);
> > }
> > @@ -272,7 +272,7 @@ static void sugov_update_shared(struct update_util_data
> > *hook, u64 time,
> > unsigned long util, max;
> > unsigned int next_f;
> >
> > - sugov_get_util(&util, &max);
> > + sugov_get_util(&util, &max, hook->cpu);
> >
>
> And here?
>
> > raw_spin_lock(&sg_policy->update_lock);
The lock prevents the same here though.
So, if we are going to use this series, then we can use the same update-lock in
case of single cpu per policies as well.
--
viresh
