eas-dev August 2020

eas-dev@lists.linaro.org

3 participants
2 discussions

Question about find_energy_effecient_cpu always return prev_cpu if task set uclamp min to 1024

by 向澐

In find_energy_effecient_cpu(), if we set a task min util clamp to 1024, all cpus will be skipped because of !fit_capcity() condition. And the return value will always be prev_cpu (best_energy_cpu initial value). For this case is it better to find max spare capcity CPU in the whole system? ex. diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index da3e5b54715b..7e431195753e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6536,6 +6536,8 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) unsigned long prev_delta = ULONG_MAX, best_delta = ULONG_MAX; struct root_domain *rd = cpu_rq(smp_processor_id())->rd; unsigned long cpu_cap, util, base_energy = 0; + unsigned long sys_max_spare_cap = 0; + int sys_max_spare_cap_cpu = prev_cpu; int cpu, best_energy_cpu = prev_cpu; struct sched_domain *sd; struct perf_domain *pd; @@ -6576,6 +6578,14 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) cpu_cap = capacity_of(cpu); spare_cap = cpu_cap - util; + /* + * Find the CPU with the maximum spare capacity in + * the performance domain + */ + if (spare_cap > sys_max_spare_cap) { + sys_max_spare_cap = spare_cap; + sys_max_spare_cap_cpu = cpu; + } /* * Skip CPUs that cannot satisfy the capacity request. * IOW, placing the task there would make the CPU @@ -6622,7 +6632,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) * least 6% of the energy used by prev_cpu. */ if (prev_delta == ULONG_MAX) - return best_energy_cpu; + return sys_max_spare_cap_cpu; if ((prev_delta - best_delta) > ((prev_delta + base_energy) >> 4)) return best_energy_cpu; Best Regards, Yun

4 years, 11 months

[Integration Branch] Update 24-July-2020

by Dietmar Eggemann

Hi, A new EAS integration branch eas/next/integration is available on http://linux-arm.org/git?p=linux-power.git For further information about main features, test coverage and work items for next integration have a look at: https://developer.arm.com/tools-and-software/open-source-software/linux-ker… Best Regards, -- Dietmar

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eas-dev August 2020