linux-kernel - RE: [PATCH 7/8] cpufreq: amd-pstate: Optimize amd_pstate_update

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Message-ID:
 <CYYPR12MB86550D88264815DA8425FF259C942@CYYPR12MB8655.namprd12.prod.outlook.com>
Date: Tue, 27 Aug 2024 06:48:56 +0000
From: "Yuan, Perry" <Perry.Yuan@....com>
To: Mario Limonciello <superm1@...nel.org>, Borislav Petkov <bp@...en8.de>,
	"Shenoy, Gautham Ranjal" <gautham.shenoy@....com>
CC: "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
	"Rafael J . Wysocki" <rafael@...nel.org>, "open list:X86 ARCHITECTURE (32-BIT
 AND 64-BIT)" <linux-kernel@...r.kernel.org>, "open list:ACPI"
	<linux-acpi@...r.kernel.org>, "open list:CPU FREQUENCY SCALING FRAMEWORK"
	<linux-pm@...r.kernel.org>, "Limonciello, Mario" <Mario.Limonciello@....com>
Subject: RE: [PATCH 7/8] cpufreq: amd-pstate: Optimize
 amd_pstate_update_limits()

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Mario Limonciello <superm1@...nel.org>
> Sent: Tuesday, August 27, 2024 5:14 AM
> To: Borislav Petkov <bp@...en8.de>; Shenoy, Gautham Ranjal
> <gautham.shenoy@....com>; Yuan, Perry <Perry.Yuan@....com>
> Cc: maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT) <x86@...nel.org>;
> Rafael J . Wysocki <rafael@...nel.org>; open list:X86 ARCHITECTURE (32-BIT
> AND 64-BIT) <linux-kernel@...r.kernel.org>; open list:ACPI <linux-
> acpi@...r.kernel.org>; open list:CPU FREQUENCY SCALING FRAMEWORK
> <linux-pm@...r.kernel.org>; Limonciello, Mario
> <Mario.Limonciello@....com>
> Subject: [PATCH 7/8] cpufreq: amd-pstate: Optimize
> amd_pstate_update_limits()
>
> From: Mario Limonciello <mario.limonciello@....com>
>
> Don't take and release the mutex when prefcore isn't present and avoid
> initialization of variables that will be initially set in the function.
>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  drivers/cpufreq/amd-pstate.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 75568d0f84623..ed05d7a0add10 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -798,17 +798,17 @@ static void amd_pstate_update_limits(unsigned int
> cpu)
>       int ret;
>       bool highest_perf_changed = false;
>
> -     mutex_lock(&amd_pstate_driver_lock);
> -     if ((!amd_pstate_prefcore) || (!cpudata->hw_prefcore))
> -             goto free_cpufreq_put;
> +     if (!amd_pstate_prefcore)
> +             return;
>
> +     mutex_lock(&amd_pstate_driver_lock);
>       ret = amd_get_highest_perf(cpu, &cur_high);
>       if (ret)
>               goto free_cpufreq_put;
>
>       prev_high = READ_ONCE(cpudata->prefcore_ranking);
> -     if (prev_high != cur_high) {
> -             highest_perf_changed = true;
> +     highest_perf_changed = (prev_high != cur_high);
> +     if (highest_perf_changed) {
>               WRITE_ONCE(cpudata->prefcore_ranking, cur_high);
>
>               if (cur_high < CPPC_MAX_PERF)
> --
> 2.43.0
>

Reviewed-by: Perry Yuan <perry.yuan@....com>


Best Regards.

Perry.