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From: Oleksandr Natalenko <oleksandr@natalenko.name>
To: rafael@kernel.org, Lucas Lee Jing Yi <lucasleeeeeeeee@gmail.com>
Cc: Perry.Yuan@amd.com, Xiaojian.Du@amd.com,
	alexander.deucher@amd.com, bp@alien8.de, deepak.sharma@amd.com,
	li.meng@amd.com, linux-acpi@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-pm@vger.kernel.org, mario.limonciello@amd.com,
	nathan.fontenot@amd.com, rafael.j.wysocki@intel.com,
	ray.huang@amd.com, shimmer.huang@amd.com,
	skhan@linuxfoundation.org, viresh.kumar@linaro.org,
	x86@kernel.org, Lucas Lee Jing Yi <lucasleeeeeeeee@gmail.com>
Subject: Re: [PATCH] [PATCH] amd_pstate: fix erroneous highest_perf value on some CPUs
Date: Tue, 20 Feb 2024 10:02:48 +0100	[thread overview]
Message-ID: <3868832.mvXUDI8C0e@natalenko.name> (raw)
In-Reply-To: <20240218161435.38312-2-lucasleeeeeeeee@gmail.com>

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Hello.

On neděle 18. února 2024 17:10:31 CET Lucas Lee Jing Yi wrote:
> On a Ryzen 7840HS the highest_perf value is 196, not 166 as AMD assumed.
> This leads to the advertised max clock speed to only be 4.35ghz instead of 5.14ghz , leading to a large degradation in performance.
> 
> Fix the broken assumption and revert back to the old logic for getting highest_perf.
> 
> TEST:
> Geekbench 6 Before Patch:
> Single Core:	2325 (-22%)!
> Multi Core:	11335 (-10%)
> 
> Geekbench 6 AFTER Patch:
> Single Core:	2635
> Multi Core:	12487
> 
> Signed-off-by: Lucas Lee Jing Yi <lucasleeeeeeeee@gmail.com>
> ---
>  drivers/cpufreq/amd-pstate.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 08e112444c27..54df68773620 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -50,7 +50,6 @@
>  
>  #define AMD_PSTATE_TRANSITION_LATENCY	20000
>  #define AMD_PSTATE_TRANSITION_DELAY	1000
> -#define AMD_PSTATE_PREFCORE_THRESHOLD	166
>  
>  /*
>   * TODO: We need more time to fine tune processors with shared memory solution
> @@ -299,15 +298,12 @@ static int pstate_init_perf(struct amd_cpudata *cpudata)
>  				     &cap1);
>  	if (ret)
>  		return ret;
> -
> -	/* For platforms that do not support the preferred core feature, the
> -	 * highest_pef may be configured with 166 or 255, to avoid max frequency
> -	 * calculated wrongly. we take the AMD_CPPC_HIGHEST_PERF(cap1) value as
> -	 * the default max perf.
> + 
> +	/* Some CPUs have different highest_perf from others, it is safer 
> +	 * to read it than to assume some erroneous value, leading to performance issues.
>  	 */
> -	if (cpudata->hw_prefcore)
> -		highest_perf = AMD_PSTATE_PREFCORE_THRESHOLD;
> -	else
> +	highest_perf = amd_get_highest_perf();
> +	if(highest_perf > AMD_CPPC_HIGHEST_PERF(cap1))
>  		highest_perf = AMD_CPPC_HIGHEST_PERF(cap1);
>  
>  	WRITE_ONCE(cpudata->highest_perf, highest_perf);
> @@ -329,9 +325,11 @@ static int cppc_init_perf(struct amd_cpudata *cpudata)
>  	if (ret)
>  		return ret;
>  
> -	if (cpudata->hw_prefcore)
> -		highest_perf = AMD_PSTATE_PREFCORE_THRESHOLD;
> -	else
> +	/* Some CPUs have different highest_perf from others, it is safer 
> +	 * to read it than to assume some erroneous value, leading to performance issues.
> +	 */
> +	highest_perf = amd_get_highest_perf();
> +	if(highest_perf > cppc_perf.highest_perf)
>  		highest_perf = cppc_perf.highest_perf;
>  
>  	WRITE_ONCE(cpudata->highest_perf, highest_perf);
> 

Please pay attention to trailing whitespaces, adding whitespaces to blank lines, and whitespaces between `if` and opening `(`.

`scripts/checkpatch.pl` may help you with that.

Thank you.

-- 
Oleksandr Natalenko (post-factum)

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  parent reply	other threads:[~2024-02-20  9:03 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-19  9:04 [PATCH V14 0/7] amd-pstate preferred core Meng Li
2024-01-19  9:04 ` [PATCH V14 1/7] x86: Drop CPU_SUP_INTEL from SCHED_MC_PRIO for the expansion Meng Li
2024-01-19  9:04 ` [PATCH V14 2/7] ACPI: CPPC: Add get the highest performance cppc control Meng Li
2024-01-19  9:04 ` [PATCH V14 3/7] cpufreq: amd-pstate: Enable amd-pstate preferred core supporting Meng Li
2024-01-19  9:04 ` [PATCH V14 4/7] cpufreq: Add a notification message that the highest perf has changed Meng Li
2024-01-19  9:05 ` [PATCH V14 5/7] cpufreq: amd-pstate: Update amd-pstate preferred core ranking dynamically Meng Li
2024-01-19  9:05 ` [PATCH V14 6/7] Documentation: amd-pstate: introduce amd-pstate preferred core Meng Li
2024-01-19  9:05 ` [PATCH V14 7/7] Documentation: introduce amd-pstate preferrd core mode kernel command line options Meng Li
2024-01-29 15:18 ` [PATCH V14 0/7] amd-pstate preferred core Rafael J. Wysocki
2024-01-29 15:33   ` Borislav Petkov
2024-01-31 13:58     ` Rafael J. Wysocki
2024-02-18 16:10       ` Lucas Lee Jing Yi
2024-02-18 16:10         ` [PATCH] [PATCH] amd_pstate: fix erroneous highest_perf value on some CPUs Lucas Lee Jing Yi
2024-02-20  7:23           ` Meng, Li (Jassmine)
2024-02-20  9:02           ` Oleksandr Natalenko [this message]
2024-02-21 17:19             ` Lucas Lee Jing Yi
2024-02-21 17:19               ` Lucas Lee Jing Yi
2024-02-21 18:47                 ` Mario Limonciello
2024-02-19  1:02         ` [PATCH V14 0/7] amd-pstate preferred core Meng, Li (Jassmine)

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