linux-kernel - Re: [PATCH] cpufreq: amd-pstate: fix the highest frequency issue which limit performance

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Date: Sun, 19 May 2024 00:07:24 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: stable@...r.kernel.org
Cc: rafael.j.wysocki@...el.com, Mario.Limonciello@....com, 
	viresh.kumar@...aro.org, Ray.Huang@....com, gautham.shenoy@....com, 
	Borislav.Petkov@....com, Alexander.Deucher@....com, Xinmei.Huang@....com, 
	Xiaojian.Du@....com, Li.Meng@....com, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Perry Yuan <perry.yuan@....com>
Subject: Re: [PATCH] cpufreq: amd-pstate: fix the highest frequency issue
 which limit performance

Hi stable team,

Please backport the mainline commit
bf202e654bfa ("cpufreq: amd-pstate: fix the highest frequency issue which limits performance")
to the 6.9 stable series.

It fixes a performance regression on AMD Phoenix platforms.

It was meant to get into the 6.9 release or the stable branch shortly
after, but apparently that didn't happen.

On 2024-05-08 13:47:03+0000, Perry Yuan wrote:
> To address the performance drop issue, an optimization has been
> implemented. The incorrect highest performance value previously set by the
> low-level power firmware for AMD CPUs with Family ID 0x19 and Model ID
> ranging from 0x70 to 0x7F series has been identified as the cause.
> 
> To resolve this, a check has been implemented to accurately determine the
> CPU family and model ID. The correct highest performance value is now set
> and the performance drop caused by the incorrect highest performance value
> are eliminated.
> 
> Before the fix, the highest frequency was set to 4200MHz, now it is set
> to 4971MHz which is correct.
> 
> CPU NODE SOCKET CORE L1d:L1i:L2:L3 ONLINE    MAXMHZ   MINMHZ       MHZ
>   0    0      0    0 0:0:0:0          yes 4971.0000 400.0000  400.0000
>   1    0      0    0 0:0:0:0          yes 4971.0000 400.0000  400.0000
>   2    0      0    1 1:1:1:0          yes 4971.0000 400.0000 4865.8140
>   3    0      0    1 1:1:1:0          yes 4971.0000 400.0000  400.0000
> 
> v1->v2:
>  * add test by flag from Gaha Bana
> 
> Fixes: f3a052391822 ("cpufreq: amd-pstate: Enable amd-pstate preferred core support")
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218759
> Signed-off-by: Perry Yuan <perry.yuan@....com>
> Co-developed-by: Mario Limonciello <mario.limonciello@....com>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> Tested-by: Gaha Bana <gahabana@...il.com>
> ---
>  drivers/cpufreq/amd-pstate.c | 22 +++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 2db095867d03..6a342b0c0140 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -50,7 +50,8 @@
>  
>  #define AMD_PSTATE_TRANSITION_LATENCY	20000
>  #define AMD_PSTATE_TRANSITION_DELAY	1000
> -#define AMD_PSTATE_PREFCORE_THRESHOLD	166
> +#define CPPC_HIGHEST_PERF_PERFORMANCE	196
> +#define CPPC_HIGHEST_PERF_DEFAULT	166
>  
>  /*
>   * TODO: We need more time to fine tune processors with shared memory solution
> @@ -326,6 +327,21 @@ static inline int amd_pstate_enable(bool enable)
>  	return static_call(amd_pstate_enable)(enable);
>  }
>  
> +static u32 amd_pstate_highest_perf_set(struct amd_cpudata *cpudata)
> +{
> +	struct cpuinfo_x86 *c = &cpu_data(0);
> +
> +	/*
> +	 * For AMD CPUs with Family ID 19H and Model ID range 0x70 to 0x7f,
> +	 * the highest performance level is set to 196.
> +	 * https://bugzilla.kernel.org/show_bug.cgi?id=218759
> +	 */
> +	if (c->x86 == 0x19 && (c->x86_model >= 0x70 && c->x86_model <= 0x7f))
> +		return CPPC_HIGHEST_PERF_PERFORMANCE;
> +
> +	return CPPC_HIGHEST_PERF_DEFAULT;
> +}
> +
>  static int pstate_init_perf(struct amd_cpudata *cpudata)
>  {
>  	u64 cap1;
> @@ -342,7 +358,7 @@ static int pstate_init_perf(struct amd_cpudata *cpudata)
>  	 * the default max perf.
>  	 */
>  	if (cpudata->hw_prefcore)
> -		highest_perf = AMD_PSTATE_PREFCORE_THRESHOLD;
> +		highest_perf = amd_pstate_highest_perf_set(cpudata);
>  	else
>  		highest_perf = AMD_CPPC_HIGHEST_PERF(cap1);
>  
> @@ -366,7 +382,7 @@ static int cppc_init_perf(struct amd_cpudata *cpudata)
>  		return ret;
>  
>  	if (cpudata->hw_prefcore)
> -		highest_perf = AMD_PSTATE_PREFCORE_THRESHOLD;
> +		highest_perf = amd_pstate_highest_perf_set(cpudata);
>  	else
>  		highest_perf = cppc_perf.highest_perf;
>  
> -- 
> 2.34.1
>