Messages in this thread | | | Subject | Re: [PATCH v3 5/5] powercap/drivers/dtpm: Scale the power with the load | From | Lukasz Luba <> | Date | Wed, 10 Mar 2021 11:22:10 +0000 |
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On 3/10/21 11:02 AM, Daniel Lezcano wrote: > Currently the power consumption is based on the current OPP power > assuming the entire performance domain is fully loaded. > > That gives very gross power estimation and we can do much better by > using the load to scale the power consumption. > > Use the utilization to normalize and scale the power usage over the > max possible power. > > Tested on a rock960 with 2 big CPUS, the power consumption estimation > conforms with the expected one. > > Before this change: > > ~$ ~/dhrystone -t 1 -l 10000& > ~$ cat /sys/devices/virtual/powercap/dtpm/dtpm:0/dtpm:0:1/constraint_0_max_power_uw > 2260000 > > After this change: > > ~$ ~/dhrystone -t 1 -l 10000& > ~$ cat /sys/devices/virtual/powercap/dtpm/dtpm:0/dtpm:0:1/constraint_0_max_power_uw > 1130000 > > ~$ ~/dhrystone -t 2 -l 10000& > ~$ cat /sys/devices/virtual/powercap/dtpm/dtpm:0/dtpm:0:1/constraint_0_max_power_uw > 2260000 > > Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> > --- > > V3: > - Fixed uninitialized 'cpu' in scaled_power_uw() > V2: > - Replaced cpumask by em_span_cpus > - Changed 'util' metrics variable types > - Optimized utilization scaling power computation > - Renamed parameter name for scale_pd_power_uw() > --- > drivers/powercap/dtpm_cpu.c | 46 +++++++++++++++++++++++++++++++------ > 1 file changed, 39 insertions(+), 7 deletions(-) > > diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c > index ac7f2e7e262f..47854923d958 100644 > --- a/drivers/powercap/dtpm_cpu.c > +++ b/drivers/powercap/dtpm_cpu.c > @@ -68,27 +68,59 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit) > return power_limit; > } > > +static u64 scale_pd_power_uw(struct cpumask *pd_mask, u64 power) > +{ > + unsigned long max = 0, sum_util = 0; > + int cpu; > + > + for_each_cpu_and(cpu, pd_mask, cpu_online_mask) { > + > + /* > + * The capacity is the same for all CPUs belonging to > + * the same perf domain, so a single call to > + * arch_scale_cpu_capacity() is enough. However, we > + * need the CPU parameter to be initialized by the > + * loop, so the call ends up in this block. > + * > + * We can initialize 'max' with a cpumask_first() call > + * before the loop but the bits computation is not > + * worth given the arch_scale_cpu_capacity() just > + * returns a value where the resulting assembly code > + * will be optimized by the compiler. > + */ > + max = arch_scale_cpu_capacity(cpu); > + sum_util += sched_cpu_util(cpu, max); > + } > + > + /* > + * In the improbable case where all the CPUs of the perf > + * domain are offline, 'max' will be zero and will lead to an > + * illegal operation with a zero division. > + */ > + return max ? (power * ((sum_util << 10) / max)) >> 10 : 0; > +} > + > static u64 get_pd_power_uw(struct dtpm *dtpm) > { > struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm); > struct em_perf_domain *pd; > - struct cpumask cpus; > + struct cpumask *pd_mask; > unsigned long freq; > - int i, nr_cpus; > + int i; > > pd = em_cpu_get(dtpm_cpu->cpu); > - freq = cpufreq_quick_get(dtpm_cpu->cpu); > > - cpumask_and(&cpus, cpu_online_mask, to_cpumask(pd->cpus)); > - nr_cpus = cpumask_weight(&cpus); > + pd_mask = em_span_cpus(pd); > + > + freq = cpufreq_quick_get(dtpm_cpu->cpu); > > for (i = 0; i < pd->nr_perf_states; i++) { > > if (pd->table[i].frequency < freq) > continue; > > - return pd->table[i].power * > - MICROWATT_PER_MILLIWATT * nr_cpus; > + return scale_pd_power_uw(pd_mask, pd->table[i].power * > + MICROWATT_PER_MILLIWATT); > } > > return 0; >
LGTM
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
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