| Message ID | c121a20eff05565155852c070e83504bf117da3e.1501223897.git.viresh.kumar@linaro.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Delegated to: | Rafael Wysocki |
| Headers | show |
On Thu, Jul 27, 2017 at 11:46 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote: > On many platforms, CPUs can do DVFS across cpufreq policies. i.e CPU > from policy-A can change frequency of CPUs belonging to policy-B. > > This is quite common in case of ARM platforms where we don't > configure any per-cpu register. > > Add a flag to identify such platforms and update > cpufreq_can_do_remote_dvfs() to allow remote callbacks if this flag is > set. > > Also enable the flag for cpufreq-dt driver which is used only on ARM > platforms currently. > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > drivers/cpufreq/cpufreq-dt.c | 1 + > include/linux/cpufreq.h | 18 ++++++++++++++++-- > 2 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c > index fef3c2160691..d83ab94d041a 100644 > --- a/drivers/cpufreq/cpufreq-dt.c > +++ b/drivers/cpufreq/cpufreq-dt.c > @@ -274,6 +274,7 @@ static int cpufreq_init(struct cpufreq_policy *policy) > transition_latency = CPUFREQ_ETERNAL; > > policy->cpuinfo.transition_latency = transition_latency; > + policy->dvfs_possible_from_any_cpu = true; > Are there also ARM hardware that may not support it? If yes, wouldn't a saner thing to do be to keep default as false and read the property from DT for hardware that does support it and then set to true? thanks, -Joel
On 28-07-17, 20:43, Joel Fernandes wrote: > On Thu, Jul 27, 2017 at 11:46 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote: > > On many platforms, CPUs can do DVFS across cpufreq policies. i.e CPU > > from policy-A can change frequency of CPUs belonging to policy-B. > > > > This is quite common in case of ARM platforms where we don't > > configure any per-cpu register. > > > > Add a flag to identify such platforms and update > > cpufreq_can_do_remote_dvfs() to allow remote callbacks if this flag is > > set. > > > > Also enable the flag for cpufreq-dt driver which is used only on ARM > > platforms currently. > > > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > > --- > > drivers/cpufreq/cpufreq-dt.c | 1 + > > include/linux/cpufreq.h | 18 ++++++++++++++++-- > > 2 files changed, 17 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c > > index fef3c2160691..d83ab94d041a 100644 > > --- a/drivers/cpufreq/cpufreq-dt.c > > +++ b/drivers/cpufreq/cpufreq-dt.c > > @@ -274,6 +274,7 @@ static int cpufreq_init(struct cpufreq_policy *policy) > > transition_latency = CPUFREQ_ETERNAL; > > > > policy->cpuinfo.transition_latency = transition_latency; > > + policy->dvfs_possible_from_any_cpu = true; > > > > Are there also ARM hardware that may not support it? I don't think so. ARM never had any per-cpu register interface which may break due to this. > If yes, wouldn't > a saner thing to do be to keep default as false and read the property > from DT for hardware that does support it and then set to true? I would do it if required, but for now I don't think there are any such users of cpufreq-dt.
On 07/27/2017 11:46 PM, Viresh Kumar wrote: > On many platforms, CPUs can do DVFS across cpufreq policies. i.e CPU > from policy-A can change frequency of CPUs belonging to policy-B. > > This is quite common in case of ARM platforms where we don't > configure any per-cpu register. > > Add a flag to identify such platforms and update > cpufreq_can_do_remote_dvfs() to allow remote callbacks if this flag is > set. > > Also enable the flag for cpufreq-dt driver which is used only on ARM > platforms currently. > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > drivers/cpufreq/cpufreq-dt.c | 1 + > include/linux/cpufreq.h | 18 ++++++++++++++++-- > 2 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c > index fef3c2160691..d83ab94d041a 100644 > --- a/drivers/cpufreq/cpufreq-dt.c > +++ b/drivers/cpufreq/cpufreq-dt.c > @@ -274,6 +274,7 @@ static int cpufreq_init(struct cpufreq_policy *policy) > transition_latency = CPUFREQ_ETERNAL; > > policy->cpuinfo.transition_latency = transition_latency; > + policy->dvfs_possible_from_any_cpu = true; > > return 0; > > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > index b3b6e8203e82..227cd0f13300 100644 > --- a/include/linux/cpufreq.h > +++ b/include/linux/cpufreq.h > @@ -127,6 +127,15 @@ struct cpufreq_policy { > */ > unsigned int transition_delay_us; > > + /* > + * Remote DVFS flag (Not added to the driver structure as we don't want > + * to access another structure from scheduler hotpath). > + * > + * Should be set if CPUs can do DVFS on behalf of other CPUs from > + * different cpufreq policies. > + */ > + bool dvfs_possible_from_any_cpu; > + Seems reasonable. This is something that can be easily set by the driver. > /* Cached frequency lookup from cpufreq_driver_resolve_freq. */ > unsigned int cached_target_freq; > int cached_resolved_idx; > @@ -564,8 +573,13 @@ struct governor_attr { > > static inline bool cpufreq_can_do_remote_dvfs(struct cpufreq_policy *policy) > { > - /* Allow remote callbacks only on the CPUs sharing cpufreq policy */ > - if (cpumask_test_cpu(smp_processor_id(), policy->cpus)) > + /* > + * Allow remote callbacks if: > + * - dvfs_possible_from_any_cpu flag is set > + * - the local and remote CPUs share cpufreq policy > + */ > + if (policy->dvfs_possible_from_any_cpu || > + cpumask_test_cpu(smp_processor_id(), policy->cpus)) > return true; > > return false; > Acked-by: Saravana Kannan <skannan@codeaurora.org>
On Fri, Jul 28, 2017 at 12:16 PM, Viresh Kumar <viresh.kumar@linaro.org> wrote: > On many platforms, CPUs can do DVFS across cpufreq policies. i.e CPU > from policy-A can change frequency of CPUs belonging to policy-B. > > This is quite common in case of ARM platforms where we don't > configure any per-cpu register. > > Add a flag to identify such platforms and update > cpufreq_can_do_remote_dvfs() to allow remote callbacks if this flag is > set. > > Also enable the flag for cpufreq-dt driver which is used only on ARM > platforms currently. > > Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> > --- > drivers/cpufreq/cpufreq-dt.c | 1 + > include/linux/cpufreq.h | 18 ++++++++++++++++-- > 2 files changed, 17 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c > index fef3c2160691..d83ab94d041a 100644 > --- a/drivers/cpufreq/cpufreq-dt.c > +++ b/drivers/cpufreq/cpufreq-dt.c > @@ -274,6 +274,7 @@ static int cpufreq_init(struct cpufreq_policy *policy) > transition_latency = CPUFREQ_ETERNAL; > > policy->cpuinfo.transition_latency = transition_latency; > + policy->dvfs_possible_from_any_cpu = true; > > return 0; > > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > index b3b6e8203e82..227cd0f13300 100644 > --- a/include/linux/cpufreq.h > +++ b/include/linux/cpufreq.h > @@ -127,6 +127,15 @@ struct cpufreq_policy { > */ > unsigned int transition_delay_us; > > + /* > + * Remote DVFS flag (Not added to the driver structure as we don't want > + * to access another structure from scheduler hotpath). > + * > + * Should be set if CPUs can do DVFS on behalf of other CPUs from > + * different cpufreq policies. > + */ > + bool dvfs_possible_from_any_cpu; > + > /* Cached frequency lookup from cpufreq_driver_resolve_freq. */ > unsigned int cached_target_freq; > int cached_resolved_idx; > @@ -564,8 +573,13 @@ struct governor_attr { > > static inline bool cpufreq_can_do_remote_dvfs(struct cpufreq_policy *policy) > { > - /* Allow remote callbacks only on the CPUs sharing cpufreq policy */ > - if (cpumask_test_cpu(smp_processor_id(), policy->cpus)) > + /* > + * Allow remote callbacks if: > + * - dvfs_possible_from_any_cpu flag is set > + * - the local and remote CPUs share cpufreq policy > + */ > + if (policy->dvfs_possible_from_any_cpu || > + cpumask_test_cpu(smp_processor_id(), policy->cpus)) > return true; > > return false; Currently sugov threads in the schedutil governor are pinned to the policy CPUs. schedutil can now make use of this new dvfs_possible_from_any_cpu flag and avoid the pinning, right? Thanks, Pavan
diff --git a/drivers/cpufreq/cpufreq-dt.c b/drivers/cpufreq/cpufreq-dt.c index fef3c2160691..d83ab94d041a 100644 --- a/drivers/cpufreq/cpufreq-dt.c +++ b/drivers/cpufreq/cpufreq-dt.c @@ -274,6 +274,7 @@ static int cpufreq_init(struct cpufreq_policy *policy) transition_latency = CPUFREQ_ETERNAL; policy->cpuinfo.transition_latency = transition_latency; + policy->dvfs_possible_from_any_cpu = true; return 0; diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index b3b6e8203e82..227cd0f13300 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -127,6 +127,15 @@ struct cpufreq_policy { */ unsigned int transition_delay_us; + /* + * Remote DVFS flag (Not added to the driver structure as we don't want + * to access another structure from scheduler hotpath). + * + * Should be set if CPUs can do DVFS on behalf of other CPUs from + * different cpufreq policies. + */ + bool dvfs_possible_from_any_cpu; + /* Cached frequency lookup from cpufreq_driver_resolve_freq. */ unsigned int cached_target_freq; int cached_resolved_idx; @@ -564,8 +573,13 @@ struct governor_attr { static inline bool cpufreq_can_do_remote_dvfs(struct cpufreq_policy *policy) { - /* Allow remote callbacks only on the CPUs sharing cpufreq policy */ - if (cpumask_test_cpu(smp_processor_id(), policy->cpus)) + /* + * Allow remote callbacks if: + * - dvfs_possible_from_any_cpu flag is set + * - the local and remote CPUs share cpufreq policy + */ + if (policy->dvfs_possible_from_any_cpu || + cpumask_test_cpu(smp_processor_id(), policy->cpus)) return true; return false;
On many platforms, CPUs can do DVFS across cpufreq policies. i.e CPU from policy-A can change frequency of CPUs belonging to policy-B. This is quite common in case of ARM platforms where we don't configure any per-cpu register. Add a flag to identify such platforms and update cpufreq_can_do_remote_dvfs() to allow remote callbacks if this flag is set. Also enable the flag for cpufreq-dt driver which is used only on ARM platforms currently. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/cpufreq-dt.c | 1 + include/linux/cpufreq.h | 18 ++++++++++++++++-- 2 files changed, 17 insertions(+), 2 deletions(-)