Messages in this thread | | | Subject | Re: [PATCH v4 1/5] arch_topology: Introduce thermal pressure update function | From | Thara Gopinath <> | Date | Tue, 16 Nov 2021 18:39:36 -0500 |
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On 11/9/21 2:57 PM, Lukasz Luba wrote: > The thermal pressure is a mechanism which is used for providing > information about reduced CPU performance to the scheduler. Usually code > has to convert the value from frequency units into capacity units, > which are understandable by the scheduler. Create a common conversion code > which can be just used via a handy API. > > Internally, the topology_update_thermal_pressure() operates on frequency > in MHz and max CPU frequency is taken from 'freq_factor' (per-cpu). > > Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Thara Gopinath <thara.gopinath@linaro.org>
-- Warm Regards Thara (She/Her/Hers)
> --- > arch/arm/include/asm/topology.h | 1 + > arch/arm64/include/asm/topology.h | 1 + > drivers/base/arch_topology.c | 43 ++++++++++++++++++++++++++++++- > include/linux/arch_topology.h | 3 +++ > include/linux/sched/topology.h | 7 +++++ > 5 files changed, 54 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h > index 470299ee2fba..f1eafacc9a30 100644 > --- a/arch/arm/include/asm/topology.h > +++ b/arch/arm/include/asm/topology.h > @@ -24,6 +24,7 @@ > /* Replace task scheduler's default thermal pressure API */ > #define arch_scale_thermal_pressure topology_get_thermal_pressure > #define arch_set_thermal_pressure topology_set_thermal_pressure > +#define arch_update_thermal_pressure topology_update_thermal_pressure > > #else > > diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h > index ec2db3419c41..7a421cbc99ed 100644 > --- a/arch/arm64/include/asm/topology.h > +++ b/arch/arm64/include/asm/topology.h > @@ -33,6 +33,7 @@ void update_freq_counters_refs(void); > /* Replace task scheduler's default thermal pressure API */ > #define arch_scale_thermal_pressure topology_get_thermal_pressure > #define arch_set_thermal_pressure topology_set_thermal_pressure > +#define arch_update_thermal_pressure topology_update_thermal_pressure > > #include <asm-generic/topology.h> > > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > index fc0836f460fb..bed7d502c9a1 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -25,6 +25,7 @@ > static DEFINE_PER_CPU(struct scale_freq_data __rcu *, sft_data); > static struct cpumask scale_freq_counters_mask; > static bool scale_freq_invariant; > +static DEFINE_PER_CPU(u32, freq_factor) = 1; > > static bool supports_scale_freq_counters(const struct cpumask *cpus) > { > @@ -168,6 +169,47 @@ void topology_set_thermal_pressure(const struct cpumask *cpus, > } > EXPORT_SYMBOL_GPL(topology_set_thermal_pressure); > > +/** > + * topology_update_thermal_pressure() - Update thermal pressure for CPUs > + * @cpus : The related CPUs for which capacity has been reduced > + * @capped_freq : The maximum allowed frequency that CPUs can run at > + * > + * Update the value of thermal pressure for all @cpus in the mask. The > + * cpumask should include all (online+offline) affected CPUs, to avoid > + * operating on stale data when hot-plug is used for some CPUs. The > + * @capped_freq reflects the currently allowed max CPUs frequency due to > + * thermal capping. It might be also a boost frequency value, which is bigger > + * than the internal 'freq_factor' max frequency. In such case the pressure > + * value should simply be removed, since this is an indication that there is > + * no thermal throttling. The @capped_freq must be provided in kHz. > + */ > +void topology_update_thermal_pressure(const struct cpumask *cpus, > + unsigned long capped_freq) > +{ > + unsigned long max_capacity, capacity; > + u32 max_freq; > + int cpu; > + > + cpu = cpumask_first(cpus); > + max_capacity = arch_scale_cpu_capacity(cpu); > + max_freq = per_cpu(freq_factor, cpu); > + > + /* Convert to MHz scale which is used in 'freq_factor' */ > + capped_freq /= 1000; > + > + /* > + * Handle properly the boost frequencies, which should simply clean > + * the thermal pressure value. > + */ > + if (max_freq <= capped_freq) > + capacity = max_capacity; > + else > + capacity = mult_frac(max_capacity, capped_freq, max_freq); > + > + arch_set_thermal_pressure(cpus, max_capacity - capacity); > +} > +EXPORT_SYMBOL_GPL(topology_update_thermal_pressure); > + > static ssize_t cpu_capacity_show(struct device *dev, > struct device_attribute *attr, > char *buf) > @@ -220,7 +262,6 @@ static void update_topology_flags_workfn(struct work_struct *work) > update_topology = 0; > } > > -static DEFINE_PER_CPU(u32, freq_factor) = 1; > static u32 *raw_capacity; > > static int free_raw_capacity(void) > diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h > index b97cea83b25e..ace1e5dcf773 100644 > --- a/include/linux/arch_topology.h > +++ b/include/linux/arch_topology.h > @@ -59,6 +59,9 @@ static inline unsigned long topology_get_thermal_pressure(int cpu) > void topology_set_thermal_pressure(const struct cpumask *cpus, > unsigned long th_pressure); > > +void topology_update_thermal_pressure(const struct cpumask *cpus, > + unsigned long capped_freq); > + > struct cpu_topology { > int thread_id; > int core_id; > diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h > index c07bfa2d80f2..6e89a8e43aa7 100644 > --- a/include/linux/sched/topology.h > +++ b/include/linux/sched/topology.h > @@ -273,6 +273,13 @@ void arch_set_thermal_pressure(const struct cpumask *cpus, > { } > #endif > > +#ifndef arch_update_thermal_pressure > +static __always_inline > +void arch_update_thermal_pressure(const struct cpumask *cpus, > + unsigned long capped_frequency) > +{ } > +#endif > + > static inline int task_node(const struct task_struct *p) > { > return cpu_to_node(task_cpu(p)); >
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