Re: [RFCv5 PATCH 40/46] sched/cpufreq_sched: compute freq_new based on capacity_orig_of()

Juri Lelli
2015-07-09T16:21:14Z

Hi Mike,

On 08/07/15 16:22, Michael Turquette wrote:
> Quoting Morten Rasmussen (2015-07-07 11:24:23)
>> From: Juri Lelli <juri.lelli@arm.com>
>>
>> capacity is both cpu and freq scaled with EAS. We thus need to compute
>> freq_new using capacity_orig_of(), so that we properly scale back the thing
>> on heterogeneous architectures. In fact, capacity_orig_of() returns only
>> the cpu scaled part of capacity (see update_cpu_capacity()). So, to scale
>> freq_new correctly, we multiply policy->max by capacity/capacity_orig_of()
>> instead of capacity/1024.
>>
>> cc: Ingo Molnar <mingo@redhat.com>
>> cc: Peter Zijlstra <peterz@infradead.org>
>>
>> Signed-off-by: Juri Lelli <juri.lelli@arm.com>
>
> Looks good to me. Please feel free to add my Reviewed-by or Acked-by as
> appropriate.
>

Thanks for reviewing it!

Best,

- Juri

> Regards,
> Mike
>
>> ---
>> kernel/sched/cpufreq_sched.c | 2 +-
>> kernel/sched/fair.c | 2 +-
>> kernel/sched/sched.h | 2 ++
>> 3 files changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/sched/cpufreq_sched.c b/kernel/sched/cpufreq_sched.c
>> index 2968f3a..7071528 100644
>> --- a/kernel/sched/cpufreq_sched.c
>> +++ b/kernel/sched/cpufreq_sched.c
>> @@ -184,7 +184,7 @@ void cpufreq_sched_set_cap(int cpu, unsigned long capacity)
>> goto out;
>>
>> /* Convert the new maximum capacity request into a cpu frequency */
>> - freq_new = capacity * policy->max >> SCHED_CAPACITY_SHIFT;
>> + freq_new = (capacity * policy->max) / capacity_orig_of(cpu);
>>
>> /* No change in frequency? Bail and return current capacity. */
>> if (freq_new == policy->cur)
>> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> index d395bc9..f74e9d2 100644
>> --- a/kernel/sched/fair.c
>> +++ b/kernel/sched/fair.c
>> @@ -4625,7 +4625,7 @@ static unsigned long capacity_of(int cpu)
>> return cpu_rq(cpu)->cpu_capacity;
>> }
>>
>> -static unsigned long capacity_orig_of(int cpu)
>> +unsigned long capacity_orig_of(int cpu)
>> {
>> return cpu_rq(cpu)->cpu_capacity_orig;
>> }
>> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
>> index b5e27d9..1327dc7 100644
>> --- a/kernel/sched/sched.h
>> +++ b/kernel/sched/sched.h
>> @@ -1476,6 +1476,8 @@ unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
>> }
>> #endif
>>
>> +unsigned long capacity_orig_of(int cpu);
>> +
>> extern struct static_key __sched_energy_freq;
>> static inline bool sched_energy_freq(void)
>> {
>> --
>> 1.9.1
>>
>> --
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>