Messages in this thread | | | Date | Tue, 31 May 2022 10:17:01 +0200 | From | Dietmar Eggemann <> | Subject | Re: [PATCH v9 6/7] sched/fair: Remove task_util from effective utilization in feec() |
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- Vincent Donnefort <vincent.donnefort@arm.com>
On 23/05/2022 17:51, Vincent Donnefort wrote: > From: Vincent Donnefort <vincent.donnefort@arm.com>
[...]
> @@ -6834,22 +6887,36 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu) > if (!task_util_est(p)) > goto unlock; > > + eenv_task_busy_time(&eenv, p, prev_cpu); > + > for (; pd; pd = pd->next) { > - unsigned long cur_delta, spare_cap, max_spare_cap = 0; > + unsigned long cpu_cap, cpu_thermal_cap, util; > + unsigned long cur_delta, max_spare_cap = 0; > bool compute_prev_delta = false; > unsigned long base_energy_pd; > int max_spare_cap_cpu = -1; > > cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask);
Internal EAS testing of this patch-set version has revealed that this doesn't work against LTP CPU hotplug stress test. `struct cpumask *cpus` can't be used when it is empty. This can happen in case all PD CPUs are hotplugged out since we `and` the invariant PD cpumask with cpu_online_mask. We need a:
+ if (cpumask_empty(cpus)) + continue; +
here.
> - for_each_cpu_and(cpu, cpus, sched_domain_span(sd)) { > + /* Account thermal pressure for the energy estimation */ > + cpu = cpumask_first(cpus); > + cpu_thermal_cap = arch_scale_cpu_capacity(cpu); > + cpu_thermal_cap -= arch_scale_thermal_pressure(cpu);
[...]
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