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

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Date: Tue, 7 May 2024 14:38:26 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: gautham.shenoy@....com
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
 regressions@...ts.linux.dev, rafael@...nel.org,
 Perry Yuan <perry.yuan@....com>, Gaha Bana <gahabana@...il.com>
Subject: Re: [PATCH] cpufreq: amd-pstate: fix the highest frequency issue
 which limit performance

On 5/7/2024 12:48, Mario Limonciello wrote:
> From: Perry Yuan <perry.yuan@....com>
> 
> 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
> 
> 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>
> ---

One of the reporters on the bug also confirmed this helped them on 
6.9-rc7.  Here's their tag:

Tested-by: Gaha Bana <gahabana@...il.com>

> This comes from patch 10 originally by Perry in [1].  As there is a regression in 6.9
> it's pulled out separately from the rest of the series.
> This should go to 6.9 final if possible; otherwise 6.10-rc1 and CC to stable
> at that time.
> 
> [1] https://lore.kernel.org/linux-pm/cover.1715065568.git.perry.yuan@amd.com/T/#t.
> 
>   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 fbe57d356ee4..4859902eaf1a 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
> @@ -264,6 +265,21 @@ 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;
> @@ -280,7 +296,7 @@ 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);
>   
> @@ -304,7 +320,7 @@ 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;
>