On Monday, August 14, 2017 11:20:16 AM CEST Viresh Kumar wrote: > The frequency update from the utilization update handlers can be divided > into two parts: > > (A) Finding the next frequency > (B) Updating the frequency > > While any CPU can do (A), (B) can be restricted to a group of CPUs only, > depending on the current platform. > > For platforms where fast cpufreq switching is possible, both (A) and (B) > are always done from the same CPU and that CPU should be capable of > changing the frequency of the target CPU. > > But for platforms where fast cpufreq switching isn't possible, after > doing (A) we wake up a kthread which will eventually do (B). This > kthread is already bound to the right set of CPUs, i.e. only those which > can change the frequency of CPUs of a cpufreq policy. And so any CPU > can actually do (A) in this case, as the frequency is updated from the > right set of CPUs only. > > Check cpufreq_can_do_remote_dvfs() only for the fast switching case. > > Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org> > --- > V2: s/policy/sg_policy->policy/, missed updating the commit with local > updates earlier, noticed that just now. > > kernel/sched/cpufreq_schedutil.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/cpufreq_schedutil.c > b/kernel/sched/cpufreq_schedutil.c > index 504d0752f8f2..9209d83ecdcf 100644 > --- a/kernel/sched/cpufreq_schedutil.c > +++ b/kernel/sched/cpufreq_schedutil.c > @@ -84,13 +84,18 @@ static bool sugov_should_update_freq(struct sugov_policy > *sg_policy, u64 time) > * > * However, drivers cannot in general deal with cross-cpu > * requests, so while get_next_freq() will work, our > - * sugov_update_commit() call may not. > + * sugov_update_commit() call may not for the fast switching platforms. > * > * Hence stop here for remote requests if they aren't supported > * by the hardware, as calculating the frequency is pointless if > * we cannot in fact act on it. > + * > + * For the slow switching platforms, the kthread is always scheduled on > + * the right set of CPUs and any CPU can find the next frequency and > + * schedule the kthread. > */ > - if (!cpufreq_can_do_remote_dvfs(sg_policy->policy)) > + if (sg_policy->policy->fast_switch_enabled && > + !cpufreq_can_do_remote_dvfs(sg_policy->policy)) > return false; > > if (sg_policy->work_in_progress) >
Applied, thanks!
