linux-kernel - Re: [PATCH PATCH v2 2/9] cpufreq: intel_pstate: Use topology_cpu

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Date: Mon, 1 Jul 2024 19:08:41 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	daniel.sneddon@...ux.intel.com, tony.luck@...el.com, 
	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, Josh Poimboeuf <jpoimboe@...nel.org>, 
	Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>, 
	"Liang, Kan" <kan.liang@...ux.intel.com>, Andrew Cooper <andrew.cooper3@...rix.com>, 
	Brice Goglin <brice.goglin@...il.com>, Mario Limonciello <mario.limonciello@....com>, 
	Perry Yuan <Perry.Yuan@....com>, Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: Re: [PATCH PATCH v2 2/9] cpufreq: intel_pstate: Use topology_cpu_type()

On Thu, Jun 27, 2024 at 10:44 PM Pawan Gupta
<pawan.kumar.gupta@...ux.intel.com> wrote:
>
> Intel pstate driver uses hybrid_get_type() to get the cpu-type of a given
> CPU. It uses smp_call_function_single() which is sub-optimal. Avoid it by
> using topology_hw_cpu_type(cpu) that returns the cached cpu-type.
>
> Suggested-by: Dave Hansen <dave.hansen@...ux.intel.com>
> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

and I'm assuming that it will be routed along with the rest of the series.

Thanks!

> ---
>  drivers/cpufreq/intel_pstate.c | 14 +++-----------
>  1 file changed, 3 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 15de5e3d96fd..0a1e832c7536 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -1956,24 +1956,16 @@ static int knl_get_turbo_pstate(int cpu)
>         return ret;
>  }
>
> -static void hybrid_get_type(void *data)
> -{
> -       u8 *cpu_type = data;
> -
> -       *cpu_type = get_this_hybrid_cpu_type();
> -}
> -
>  static int hwp_get_cpu_scaling(int cpu)
>  {
> -       u8 cpu_type = 0;
> +       u8 cpu_type = topology_hw_cpu_type(cpu);
>
> -       smp_call_function_single(cpu, hybrid_get_type, &cpu_type, 1);
>         /* P-cores have a smaller perf level-to-freqency scaling factor. */
> -       if (cpu_type == 0x40)
> +       if (cpu_type == X86_HW_CPU_TYPE_INTEL_CORE)
>                 return hybrid_scaling_factor;
>
>         /* Use default core scaling for E-cores */
> -       if (cpu_type == 0x20)
> +       if (cpu_type == X86_HW_CPU_TYPE_INTEL_ATOM)
>                 return core_get_scaling();
>
>         /*
>
> --