Re: [PATCH] Documentation, intel_pstate: Add a description of the intel_pstate internal governors

[Viresh Kumar]

On 5 June 2014 19:13, Prarit Bhargava <prarit@xxxxxxxxxx> wrote:
> The current documentation is incomplete wrt the intel_pstate internal
> governors.  The confusion comes from the general use internal governors
> which also use the names performance and powersave.  This patch
> differentiates between the two sets of governors.
>
> Cc: Dirk Brandewie <dirk.brandewie@xxxxxxxxx>
> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
> Cc: Jesper Nilsson <jesper.nilsson@xxxxxxxx>
> Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Ramkumar Ramachandra <artagnon@xxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Cc: linux-doc@xxxxxxxxxxxxxxx
>
> Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
> ---
>  Documentation/cpu-freq/governors.txt    |    2 +-
>  Documentation/cpu-freq/intel-pstate.txt |    8 ++++++++
>  2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/cpu-freq/governors.txt b/Documentation/cpu-freq/governors.txt
> index 77ec215..c15aa75 100644
> --- a/Documentation/cpu-freq/governors.txt
> +++ b/Documentation/cpu-freq/governors.txt
> @@ -36,7 +36,7 @@ Contents:
>  1. What Is A CPUFreq Governor?
>  ==============================
>
> -Most cpufreq drivers (in fact, all except one, longrun) or even most
> +Most cpufreq drivers (except the intel_pstate and longrun) or even most
>  cpu frequency scaling algorithms only offer the CPU to be set to one
>  frequency. In order to offer dynamic frequency scaling, the cpufreq
>  core must be able to tell these drivers of a "target frequency". So
> diff --git a/Documentation/cpu-freq/intel-pstate.txt b/Documentation/cpu-freq/intel-pstate.txt
> index e742d21..ce894cc 100644
> --- a/Documentation/cpu-freq/intel-pstate.txt
> +++ b/Documentation/cpu-freq/intel-pstate.txt
> @@ -9,6 +9,14 @@ assumed to implement internal governors by the cpufreq core. All the
>  logic for selecting the current P state is contained within the
>  driver; no external governor is used by the cpufreq core.
>
> +The Intel P-state driver has two internal governors, performance and
> +powersave.  These governors differ from the general use governors of the

s/general use/generally used ??

> +same name in the kernel.  The internal performance governor sets the
> +max_perf_pct and min_perf_pct to 100; that is, the governor selects the
> +highest available P state to maximize the performance of the core.  The
> +internal powersave governor, selects the appropriate P state based on the
> +current load on the CPU.
> +
>  Intel SandyBridge+ processors are supported.
>
>  New sysfs files for controlling P state selection have been added to
> --
> 1.7.9.3
>
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