Re: [PATCH v12 4/4] PM / Domains: Add genpd governor for CPUs

[Daniel Lezcano]

On 27/02/2019 20:58, Ulf Hansson wrote:
> As it's now perfectly possible that a PM domain managed by genpd contains
> devices belonging to CPUs, we should start to take into account the
> residency values for the idle states during the state selection process.
> The residency value specifies the minimum duration of time, the CPU or a
> group of CPUs, needs to spend in an idle state to not waste energy entering
> it.
> 
> To deal with this, let's add a new genpd governor, pm_domain_cpu_gov, that
> may be used for a PM domain that have CPU devices attached or if the CPUs
> are attached through subdomains.
> 
> The new governor computes the minimum expected idle duration time for the
> online CPUs being attached to the PM domain and its subdomains. Then in the
> state selection process, trying the deepest state first, it verifies that
> the idle duration time satisfies the state's residency value.
> 
> It should be noted that, when computing the minimum expected idle duration
> time, we use the information about the next timer/tick that is stored in
> the per CPU variable, cpuidle_devices, for the related CPUs. Future wise,
> this deserves to be improved, as there are obviously more reasons to why a
> CPU may be woken up from idle.
> 
> Cc: Lina Iyer <ilina@xxxxxxxxxxxxxx>
> Co-developed-by: Lina Iyer <lina.iyer@xxxxxxxxxx>
> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>

Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>



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