On 06-07-17, 10:49, Dietmar Eggemann wrote: > A frequency-invariant load-tracking solution based on cpufreq transition > notifier will not work for future fast frequency switching policies. > That is why a different solution is presented with this patch. > > Let cpufreq call the function arch_set_freq_scale() to pass the current > frequency, the max supported frequency and the cpumask of the related > cpus to a consumer (an arch) which defines arch_set_freq_scale(). > > The consumer has to associate arch_set_freq_scale with the name of its > own implementation foo_set_freq_scale() to overwrite the empty standard > definition in drivers/cpufreq/cpufreq.c. > An arch could do this in one of its arch-specific header files > (e.g. arch/$ARCH/include/asm/topology.h) which gets included in > drivers/cpufreq/cpufreq.c. > > In case arch_set_freq_scale() is not defined (and because of the > pr_debug() drivers/cpufreq/cpufreq.c is not compiled with -DDEBUG)
The line within () needs to be improved to convey a clear message. > the > function cpufreq_set_freq_scale() gets compiled out. > > Cc: Rafael J. Wysocki <[email protected]> > Cc: Viresh Kumar <[email protected]> > Signed-off-by: Dietmar Eggemann <[email protected]> > --- > drivers/cpufreq/cpufreq.c | 26 ++++++++++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 9bf97a366029..a04c5886a5ce 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -347,6 +347,28 @@ static void __cpufreq_notify_transition(struct > cpufreq_policy *policy, > } > } > > +/********************************************************************* > + * FREQUENCY INVARIANT CPU CAPACITY SUPPORT * > + *********************************************************************/ > + > +#ifndef arch_set_freq_scale > +static void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq, > + unsigned long max_freq) > +{} > +#endif > + > +static void cpufreq_set_freq_scale(struct cpufreq_policy *policy, > + struct cpufreq_freqs *freqs) > +{ > + unsigned long cur_freq = freqs ? freqs->new : policy->cur; > + unsigned long max_freq = policy->cpuinfo.max_freq; > + > + pr_debug("cpus %*pbl cur/cur max freq %lu/%lu kHz\n", > + cpumask_pr_args(policy->related_cpus), cur_freq, max_freq); > + > + arch_set_freq_scale(policy->related_cpus, cur_freq, max_freq); I am not sure why all these are required to be sent here and will come back to it later on after going through other patches. > +} > + > /** > * cpufreq_notify_transition - call notifier chain and adjust_jiffies > * on frequency transition. > @@ -405,6 +427,8 @@ void cpufreq_freq_transition_begin(struct cpufreq_policy > *policy, > > spin_unlock(&policy->transition_lock); > > + cpufreq_set_freq_scale(policy, freqs); > + Why do this before even changing the frequency ? We may fail while changing it. IMHO, you should call this routine whenever we update policy->cur and that happens regularly in __cpufreq_notify_transition() and few other places.. > cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE); > } > EXPORT_SYMBOL_GPL(cpufreq_freq_transition_begin); > @@ -2203,6 +2227,8 @@ static int cpufreq_set_policy(struct cpufreq_policy > *policy, > blocking_notifier_call_chain(&cpufreq_policy_notifier_list, > CPUFREQ_NOTIFY, new_policy); > > + cpufreq_set_freq_scale(new_policy, NULL); Why added it here ? To get it initialized ? If yes, then we should do that in cpufreq_online() where we first initialize policy->cur. Apart from this, you also need to update this in the schedutil governor (if you haven't done that in this series later) as that also updates policy->cur in the fast path. -- viresh
