| Message ID | 20240108134843.429769-2-vincent.guittot@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Rework system pressure interface to the scheduler | expand |
On 08/01/2024 14:48, Vincent Guittot wrote: > Provide to the scheduler a feedback about the temporary max available > capacity. Unlike arch_update_thermal_pressure, this doesn't need to be > filtered as the pressure will happen for dozens ms or more. Is this then related to the 'medium pace system pressure' you mentioned in your OSPM '23 talk? > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > --- > drivers/cpufreq/cpufreq.c | 36 ++++++++++++++++++++++++++++++++++++ > include/linux/cpufreq.h | 10 ++++++++++ > 2 files changed, 46 insertions(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 44db4f59c4cc..fa2e2ea26f7f 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -2563,6 +2563,40 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu) > } > EXPORT_SYMBOL(cpufreq_get_policy); > > +DEFINE_PER_CPU(unsigned long, cpufreq_pressure); > + > +/** > + * cpufreq_update_pressure() - Update cpufreq pressure for CPUs > + * @policy: cpufreq policy of the CPUs. > + * > + * Update the value of cpufreq pressure for all @cpus in the policy. > + */ > +static void cpufreq_update_pressure(struct cpufreq_policy *policy) > +{ > + unsigned long max_capacity, capped_freq, pressure; > + u32 max_freq; > + int cpu; > + > + /* > + * Handle properly the boost frequencies, which should simply clean > + * the thermal pressure value. ^^^^^^^ IMHO, this is a copy & paste error from topology_update_thermal_pressure()? > + */ > + if (max_freq <= capped_freq) { max_freq seems to be uninitialized. > + pressure = 0; Is this x86 (turbo boost) specific? IMHO at arm we follow this max freq (including boost) relates to 1024 in capacity? Or haven't we made this discussion yet? > + } else { > + cpu = cpumask_first(policy->related_cpus); > + max_capacity = arch_scale_cpu_capacity(cpu); > + capped_freq = policy->max; > + max_freq = arch_scale_freq_ref(cpu); > + > + pressure = max_capacity - > + mult_frac(max_capacity, capped_freq, max_freq); > + } > + > + for_each_cpu(cpu, policy->related_cpus) > + WRITE_ONCE(per_cpu(cpufreq_pressure, cpu), pressure); > +} > + [...]
On Mon, 8 Jan 2024 at 17:35, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: > > On 08/01/2024 14:48, Vincent Guittot wrote: > > Provide to the scheduler a feedback about the temporary max available > > capacity. Unlike arch_update_thermal_pressure, this doesn't need to be > > filtered as the pressure will happen for dozens ms or more. > > Is this then related to the 'medium pace system pressure' you mentioned > in your OSPM '23 talk? > > > > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > > --- > > drivers/cpufreq/cpufreq.c | 36 ++++++++++++++++++++++++++++++++++++ > > include/linux/cpufreq.h | 10 ++++++++++ > > 2 files changed, 46 insertions(+) > > > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > > index 44db4f59c4cc..fa2e2ea26f7f 100644 > > --- a/drivers/cpufreq/cpufreq.c > > +++ b/drivers/cpufreq/cpufreq.c > > @@ -2563,6 +2563,40 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu) > > } > > EXPORT_SYMBOL(cpufreq_get_policy); > > > > +DEFINE_PER_CPU(unsigned long, cpufreq_pressure); > > + > > +/** > > + * cpufreq_update_pressure() - Update cpufreq pressure for CPUs > > + * @policy: cpufreq policy of the CPUs. > > + * > > + * Update the value of cpufreq pressure for all @cpus in the policy. > > + */ > > +static void cpufreq_update_pressure(struct cpufreq_policy *policy) > > +{ > > + unsigned long max_capacity, capped_freq, pressure; > > + u32 max_freq; > > + int cpu; > > + > > + /* > > + * Handle properly the boost frequencies, which should simply clean > > + * the thermal pressure value. > ^^^^^^^ > IMHO, this is a copy & paste error from topology_update_thermal_pressure()? > > > + */ > > + if (max_freq <= capped_freq) { > > max_freq seems to be uninitialized. argh yes, I made crap while cleaning up both max_freq and capped_freq are uninitialized > > > + pressure = 0; > > Is this x86 (turbo boost) specific? IMHO at arm we follow this max freq > (including boost) relates to 1024 in capacity? Or haven't we made this > discussion yet? This is not x86 specific. We can have capped_freq > max_freq on Arm too Also this bypass all calculation below when max_freq == capped_freq which is the most common case > > > + } else { > > + cpu = cpumask_first(policy->related_cpus); > > + max_capacity = arch_scale_cpu_capacity(cpu); > > + capped_freq = policy->max; > > + max_freq = arch_scale_freq_ref(cpu); > > + > > + pressure = max_capacity - > > + mult_frac(max_capacity, capped_freq, max_freq); > > + } > > + > > + for_each_cpu(cpu, policy->related_cpus) > > + WRITE_ONCE(per_cpu(cpufreq_pressure, cpu), pressure); > > +} > > + > > [...] >
On Mon, 8 Jan 2024 at 17:35, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: > > On 08/01/2024 14:48, Vincent Guittot wrote: > > Provide to the scheduler a feedback about the temporary max available > > capacity. Unlike arch_update_thermal_pressure, this doesn't need to be > > filtered as the pressure will happen for dozens ms or more. > > Is this then related to the 'medium pace system pressure' you mentioned > in your OSPM '23 talk? Sorry I forgot to answer this question. Yes this is the medium pace system pressure that I mentioned at OSPM'23 > > >
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 44db4f59c4cc..fa2e2ea26f7f 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -2563,6 +2563,40 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu) } EXPORT_SYMBOL(cpufreq_get_policy); +DEFINE_PER_CPU(unsigned long, cpufreq_pressure); + +/** + * cpufreq_update_pressure() - Update cpufreq pressure for CPUs + * @policy: cpufreq policy of the CPUs. + * + * Update the value of cpufreq pressure for all @cpus in the policy. + */ +static void cpufreq_update_pressure(struct cpufreq_policy *policy) +{ + unsigned long max_capacity, capped_freq, pressure; + u32 max_freq; + int cpu; + + /* + * Handle properly the boost frequencies, which should simply clean + * the thermal pressure value. + */ + if (max_freq <= capped_freq) { + pressure = 0; + } else { + cpu = cpumask_first(policy->related_cpus); + max_capacity = arch_scale_cpu_capacity(cpu); + capped_freq = policy->max; + max_freq = arch_scale_freq_ref(cpu); + + pressure = max_capacity - + mult_frac(max_capacity, capped_freq, max_freq); + } + + for_each_cpu(cpu, policy->related_cpus) + WRITE_ONCE(per_cpu(cpufreq_pressure, cpu), pressure); +} + /** * cpufreq_set_policy - Modify cpufreq policy parameters. * @policy: Policy object to modify. @@ -2618,6 +2652,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, policy->max = __resolve_freq(policy, policy->max, CPUFREQ_RELATION_H); trace_cpu_frequency_limits(policy); + cpufreq_update_pressure(policy); + policy->cached_target_freq = UINT_MAX; pr_debug("new min and max freqs are %u - %u kHz\n", diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index afda5f24d3dd..b1d97edd3253 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -241,6 +241,12 @@ 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); bool has_target_index(void); + +DECLARE_PER_CPU(unsigned long, cpufreq_pressure); +static inline unsigned long cpufreq_get_pressure(int cpu) +{ + return per_cpu(cpufreq_pressure, cpu); +} #else static inline unsigned int cpufreq_get(unsigned int cpu) { @@ -263,6 +269,10 @@ static inline bool cpufreq_supports_freq_invariance(void) return false; } static inline void disable_cpufreq(void) { } +static inline unsigned long cpufreq_get_pressure(int cpu) +{ + return 0; +} #endif #ifdef CONFIG_CPU_FREQ_STAT
Provide to the scheduler a feedback about the temporary max available capacity. Unlike arch_update_thermal_pressure, this doesn't need to be filtered as the pressure will happen for dozens ms or more. Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> --- drivers/cpufreq/cpufreq.c | 36 ++++++++++++++++++++++++++++++++++++ include/linux/cpufreq.h | 10 ++++++++++ 2 files changed, 46 insertions(+)