linux-kernel - Re: [PATCH 03/12] cpufreq/amd-pstate: Modify the min_perf calculation in adjust

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Message-ID: <bbbc09e9-4719-4a8a-b368-1b5aa67b6e76@amd.com>
Date: Wed, 5 Feb 2025 11:45:30 -0600
From: Mario Limonciello <mario.limonciello@....com>
To: Dhananjay Ugwekar <dhananjay.ugwekar@....com>
Cc: linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
 gautham.shenoy@....com, rafael@...nel.org, viresh.kumar@...aro.org
Subject: Re: [PATCH 03/12] cpufreq/amd-pstate: Modify the min_perf calculation
 in adjust_perf callback

On 2/5/2025 05:25, Dhananjay Ugwekar wrote:
> Instead of setting a fixed floor at lowest_nonlinear_perf, use the
> min_limit_perf value, so that it gives the user the freedom to lower the
> floor further.
> 
> There are two minimum frequency/perf limits that we need to consider in
> the adjust_perf callback. One provided by schedutil i.e. the sg_cpu->bw_min
> value passed in _min_perf arg, another is the effective value of
> min_freq_qos request that is updated in cpudata->min_limit_perf. Modify the
> code to use the bigger of these two values.
> 
> Signed-off-by: Dhananjay Ugwekar <dhananjay.ugwekar@....com>

Reviewed-by: Mario Limonciello <mario.limonciello@....com>

I'll queue this for 6.15.

> ---
>   drivers/cpufreq/amd-pstate.c | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 9dc3933bc326..a23fb78a442b 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -672,7 +672,7 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
>   				   unsigned long capacity)
>   {
>   	unsigned long max_perf, min_perf, des_perf,
> -		      cap_perf, lowest_nonlinear_perf;
> +		      cap_perf, min_limit_perf;
>   	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
>   	struct amd_cpudata *cpudata;
>   
> @@ -684,20 +684,20 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
>   	if (policy->min != cpudata->min_limit_freq || policy->max != cpudata->max_limit_freq)
>   		amd_pstate_update_min_max_limit(policy);
>   
> -
>   	cap_perf = READ_ONCE(cpudata->highest_perf);
> -	lowest_nonlinear_perf = READ_ONCE(cpudata->lowest_nonlinear_perf);
> +	min_limit_perf = READ_ONCE(cpudata->min_limit_perf);
>   
>   	des_perf = cap_perf;
>   	if (target_perf < capacity)
>   		des_perf = DIV_ROUND_UP(cap_perf * target_perf, capacity);
>   
> -	min_perf = READ_ONCE(cpudata->lowest_perf);
>   	if (_min_perf < capacity)
>   		min_perf = DIV_ROUND_UP(cap_perf * _min_perf, capacity);
> +	else
> +		min_perf = cap_perf;
>   
> -	if (min_perf < lowest_nonlinear_perf)
> -		min_perf = lowest_nonlinear_perf;
> +	if (min_perf < min_limit_perf)
> +		min_perf = min_limit_perf;
>   
>   	max_perf = cpudata->max_limit_perf;
>   	if (max_perf < min_perf)