On Tue, Feb 09, 2016 at 09:05:05PM +0100, Rafael J. Wysocki wrote: > > > One concern I had was, given that the lone scheduler update hook is in > > > CFS, is it possible for governor updates to be stalled due to RT or DL > > > task activity? > > > > I don't think they may be completely stalled, but I'd prefer Peter to > > answer that as he suggested to do it this way. > > In any case, if that concern turns out to be significant in practice, it may > be addressed like in the appended modification of patch [1/3] from the > $subject > series. > > With that things look like before from the cpufreq side, but the other sched > classes also get a chance to trigger a cpufreq update. The drawback is the > cpu_clock() call instead of passing the time value from update_load_avg(), but > I guess we can live with that if necessary. > > FWIW, this modification doesn't seem to break things on my test machine.
Not really pretty though. It blows a bit that you require this callback to be periodic (in order to replace a timer). Ideally we'd not have to call this if state doesn't change. > +++ linux-pm/include/linux/sched.h > @@ -3207,4 +3207,11 @@ static inline unsigned long rlimit_max(u > return task_rlimit_max(current, limit); > } > > +void cpufreq_update_util(unsigned long util, unsigned long max); Didn't you have a timestamp in there? > + > +static inline void cpufreq_kick(void) > +{ > + cpufreq_update_util(ULONG_MAX, ULONG_MAX); > +} > + > #endif