Re: [RFC PATCH 15/23] thermal: intel: hfi: Report per-cpu class-specific performance scores

Peter Zijlstra
2022-09-27T11:59:40Z

On Fri, Sep 09, 2022 at 04:11:57PM -0700, Ricardo Neri wrote:
> Support the arch_get_task_class_score() interface of the scheduler. Use the
> data that Intel Thread Director provides to inform the scheduler the
> performance of a class of tasks when placed on a given CPU.
>

> +static void get_one_hfi_cap(struct hfi_instance *hfi_instance, s16 index,
> + struct hfi_cpu_data *hfi_caps, int class)
> +{
> + struct hfi_cpu_data *caps;
> +
> + /* Find the capabilities of @cpu */
> + caps = hfi_instance->data + index * hfi_features.cpu_stride +
> + class * hfi_features.class_stride;
> + memcpy(hfi_caps, caps, sizeof(*hfi_caps));
> +}
> +
> +int intel_hfi_get_task_class_score(int class, int cpu)
> +{
> + struct hfi_cpu_info *info = &per_cpu(hfi_cpu_info, cpu);
> + struct hfi_instance *instance;
> + struct hfi_cpu_data caps;
> + unsigned long flags;
> + int cap;
> +
> + if (cpu < 0 || cpu >= nr_cpu_ids)
> + return -EINVAL;
> +
> + if (class == TASK_CLASS_UNCLASSIFIED)
> + return -EINVAL;
> +
> + if (class >= (int)hfi_features.nr_classes)
> + return -EINVAL;
> +
> + instance = info->hfi_instance;
> + if (!instance)
> + return -ENOENT;
> +
> + raw_spin_lock_irqsave(&instance->table_lock, flags);
> + get_one_hfi_cap(instance, info->index, &caps, class);
> + cap = caps.perf_cap;
> + raw_spin_unlock_irqrestore(&instance->table_lock, flags);
> +
> + return cap;
> +}

Does any of that data actually ever change? Isn't the class score fixed
per CPU type?