Re: [PATCH v3 1/2] power: introduce PM QoS API on CPU wide

[Stephen Hemminger <stephen@networkplumber.org>]

On Wed, 19 Jun 2024 14:31:43 +0800
Huisong Li <lihuisong@huawei.com> wrote:

> +PM QoS
> +------
> +
> +The deeper the idle state, the lower the power consumption, but the longer
> +the resume time. Some service are delay sensitive and very except the low
> +resume time, like interrupt packet receiving mode.
> +
> +And the "/sys/devices/system/cpu/cpuX/power/pm_qos_resume_latency_us" sysfs
> +interface is used to set and get the resume latency limit on the cpuX for
> +userspace. Each cpuidle governor in Linux select which idle state to enter
> +based on this CPU resume latency in their idle task.
> +
> +The per-CPU PM QoS API can be used to set and get the CPU resume latency.
> +
> +The ``rte_power_qos_set_cpu_resume_latency()`` function can effect the work
> +CPU's idle state selection and just allow to enter the shallowest idle state
> +if set to zero (strict resume latency) for this CPU.
> +
> +The ``rte_power_qos_get_cpu_resume_latency()`` function can obtain the resume
> +latency on specified CPU.
> +

Wording of this is hard to read and needs to be reworded for clarity.
Explain more what PM QoS is to the user.
Also, not sure if details about sysfs implementation is helpful.
Should also say this is Linux only.