| Message ID | 20200824210252.27486-4-ionela.voinescu@arm.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | cpufreq: improve frequency invariance support | expand |
On 24-08-20, 22:02, Ionela Voinescu wrote: > Now that the update of the FI scale factor is done in cpufreq core for > selected functions - target(), target_index() and fast_switch(), > we can provide feedback to the task scheduler and architecture code > on whether cpufreq supports FI. > > For this purpose provide an external function to expose whether the > cpufreq drivers support FI, by using a static key. > > The logic behind the enablement of cpufreq-based invariance is as > follows: > - cpufreq-based invariance is disabled by default > - cpufreq-based invariance is enabled if any of the callbacks > above is implemented while the unsupported setpolicy() is not > > The cpufreq_supports_freq_invariance() function only returns whether > cpufreq is instrumented with the arch_set_freq_scale() calls that > result in support for frequency invariance. Due to the lack of knowledge > on whether the implementation of arch_set_freq_scale() actually results > in the setting of a scale factor based on cpufreq information, it is up > to the architecture code to ensure the setting and provision of the > scale factor to the scheduler. > > Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com> > Cc: Rafael J. Wysocki <rjw@rjwysocki.net> > Cc: Viresh Kumar <viresh.kumar@linaro.org> > --- > drivers/cpufreq/cpufreq.c | 20 ++++++++++++++++++++ > include/linux/cpufreq.h | 5 +++++ > 2 files changed, 25 insertions(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 34533c6b3bd0..b3a7d1cc5e92 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -61,6 +61,9 @@ static struct cpufreq_driver *cpufreq_driver; > static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data); > static DEFINE_RWLOCK(cpufreq_driver_lock); > > +/* Mark support for the scheduler's frequency invariance engine */ > +static DEFINE_STATIC_KEY_FALSE(cpufreq_freq_invariance); > + > /* Flag to suspend/resume CPUFreq governors */ > static bool cpufreq_suspended; > > @@ -69,6 +72,20 @@ static inline bool has_target(void) > return cpufreq_driver->target_index || cpufreq_driver->target; > } > > +static inline > +void enable_cpufreq_freq_invariance(struct cpufreq_driver *driver) > +{ > + if (!driver->setpolicy) { > + static_branch_enable_cpuslocked(&cpufreq_freq_invariance); > + pr_debug("supports frequency invariance"); > + } > +} > + I would rather open-code this int the cpufreq_register_driver() routine as that's what is done in cpufreq_unregister_driver() as well. > +bool cpufreq_supports_freq_invariance(void) > +{ > + return static_branch_likely(&cpufreq_freq_invariance); > +} > + And would keep the definition of the static key with this routine at a single place. > /* internal prototypes */ > static unsigned int __cpufreq_get(struct cpufreq_policy *policy); > static int cpufreq_init_governor(struct cpufreq_policy *policy); > @@ -2721,6 +2738,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) > cpufreq_driver = driver_data; > write_unlock_irqrestore(&cpufreq_driver_lock, flags); > > + enable_cpufreq_freq_invariance(cpufreq_driver); > + > if (driver_data->setpolicy) > driver_data->flags |= CPUFREQ_CONST_LOOPS; > > @@ -2790,6 +2809,7 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver) > cpus_read_lock(); > subsys_interface_unregister(&cpufreq_interface); > remove_boost_sysfs_file(); > + static_branch_disable_cpuslocked(&cpufreq_freq_invariance); > cpuhp_remove_state_nocalls_cpuslocked(hp_online); > > write_lock_irqsave(&cpufreq_driver_lock, flags); > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > index 8f141d4c859c..091df9968945 100644 > --- a/include/linux/cpufreq.h > +++ b/include/linux/cpufreq.h > @@ -217,6 +217,7 @@ void refresh_frequency_limits(struct cpufreq_policy *policy); > void cpufreq_update_policy(unsigned int cpu); > void cpufreq_update_limits(unsigned int cpu); > bool have_governor_per_policy(void); > +bool cpufreq_supports_freq_invariance(void); > struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy); > void cpufreq_enable_fast_switch(struct cpufreq_policy *policy); > void cpufreq_disable_fast_switch(struct cpufreq_policy *policy); > @@ -237,6 +238,10 @@ static inline unsigned int cpufreq_get_hw_max_freq(unsigned int cpu) > { > return 0; > } > +static inline bool cpufreq_supports_freq_invariance(void) > +{ > + return false; > +} > static inline void disable_cpufreq(void) { } > #endif > > -- > 2.17.1
Hi Viresh, On Tuesday 25 Aug 2020 at 11:57:09 (+0530), Viresh Kumar wrote: [..] > > +static inline > > +void enable_cpufreq_freq_invariance(struct cpufreq_driver *driver) > > +{ > > + if (!driver->setpolicy) { > > + static_branch_enable_cpuslocked(&cpufreq_freq_invariance); > > + pr_debug("supports frequency invariance"); > > + } > > +} > > + > > I would rather open-code this int the cpufreq_register_driver() routine as > that's what is done in cpufreq_unregister_driver() as well. > > > +bool cpufreq_supports_freq_invariance(void) > > +{ > > + return static_branch_likely(&cpufreq_freq_invariance); > > +} > > + > > And would keep the definition of the static key with this routine at a single > place. Makes sense and will do! Thank you for the quick review, Ionela.
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 34533c6b3bd0..b3a7d1cc5e92 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -61,6 +61,9 @@ static struct cpufreq_driver *cpufreq_driver; static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data); static DEFINE_RWLOCK(cpufreq_driver_lock); +/* Mark support for the scheduler's frequency invariance engine */ +static DEFINE_STATIC_KEY_FALSE(cpufreq_freq_invariance); + /* Flag to suspend/resume CPUFreq governors */ static bool cpufreq_suspended; @@ -69,6 +72,20 @@ static inline bool has_target(void) return cpufreq_driver->target_index || cpufreq_driver->target; } +static inline +void enable_cpufreq_freq_invariance(struct cpufreq_driver *driver) +{ + if (!driver->setpolicy) { + static_branch_enable_cpuslocked(&cpufreq_freq_invariance); + pr_debug("supports frequency invariance"); + } +} + +bool cpufreq_supports_freq_invariance(void) +{ + return static_branch_likely(&cpufreq_freq_invariance); +} + /* internal prototypes */ static unsigned int __cpufreq_get(struct cpufreq_policy *policy); static int cpufreq_init_governor(struct cpufreq_policy *policy); @@ -2721,6 +2738,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) cpufreq_driver = driver_data; write_unlock_irqrestore(&cpufreq_driver_lock, flags); + enable_cpufreq_freq_invariance(cpufreq_driver); + if (driver_data->setpolicy) driver_data->flags |= CPUFREQ_CONST_LOOPS; @@ -2790,6 +2809,7 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver) cpus_read_lock(); subsys_interface_unregister(&cpufreq_interface); remove_boost_sysfs_file(); + static_branch_disable_cpuslocked(&cpufreq_freq_invariance); cpuhp_remove_state_nocalls_cpuslocked(hp_online); write_lock_irqsave(&cpufreq_driver_lock, flags); diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 8f141d4c859c..091df9968945 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -217,6 +217,7 @@ void refresh_frequency_limits(struct cpufreq_policy *policy); void cpufreq_update_policy(unsigned int cpu); void cpufreq_update_limits(unsigned int cpu); bool have_governor_per_policy(void); +bool cpufreq_supports_freq_invariance(void); struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy); void cpufreq_enable_fast_switch(struct cpufreq_policy *policy); void cpufreq_disable_fast_switch(struct cpufreq_policy *policy); @@ -237,6 +238,10 @@ static inline unsigned int cpufreq_get_hw_max_freq(unsigned int cpu) { return 0; } +static inline bool cpufreq_supports_freq_invariance(void) +{ + return false; +} static inline void disable_cpufreq(void) { } #endif
Now that the update of the FI scale factor is done in cpufreq core for selected functions - target(), target_index() and fast_switch(), we can provide feedback to the task scheduler and architecture code on whether cpufreq supports FI. For this purpose provide an external function to expose whether the cpufreq drivers support FI, by using a static key. The logic behind the enablement of cpufreq-based invariance is as follows: - cpufreq-based invariance is disabled by default - cpufreq-based invariance is enabled if any of the callbacks above is implemented while the unsupported setpolicy() is not The cpufreq_supports_freq_invariance() function only returns whether cpufreq is instrumented with the arch_set_freq_scale() calls that result in support for frequency invariance. Due to the lack of knowledge on whether the implementation of arch_set_freq_scale() actually results in the setting of a scale factor based on cpufreq information, it is up to the architecture code to ensure the setting and provision of the scale factor to the scheduler. Signed-off-by: Ionela Voinescu <ionela.voinescu@arm.com> Cc: Rafael J. Wysocki <rjw@rjwysocki.net> Cc: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/cpufreq.c | 20 ++++++++++++++++++++ include/linux/cpufreq.h | 5 +++++ 2 files changed, 25 insertions(+)