linux-kernel - Re: [PATCH V3 5/7] cpufreq: amd-pstate: Update AMD Pstate Preferred Core ranking dynamically

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Message-ID: <20230824110949.362p6kpcgqlfa5cj@BLR-5CG13462PL.amd.com>
Date:   Thu, 24 Aug 2023 16:48:44 +0530
From:   Wyes Karny <wyes.karny@....com>
To:     Meng Li <li.meng@....com>
CC:     Wyes Karny <wyes.karny@....com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Huang Rui <ray.huang@....com>, <linux-pm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <x86@...nel.org>,
        <linux-acpi@...r.kernel.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        <linux-kselftest@...r.kernel.org>,
        Nathan Fontenot <nathan.fontenot@....com>,
        Deepak Sharma <deepak.sharma@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        Shimmer Huang <shimmer.huang@....com>,
        Perry Yuan <Perry.Yuan@....com>,
        Xiaojian Du <Xiaojian.Du@....com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Borislav Petkov <bp@...en8.de>
Subject: Re: [PATCH V3 5/7] cpufreq: amd-pstate: Update AMD Pstate Preferred Core ranking dynamically

On 24 Aug 10:12, Meng Li wrote:
> Preferred core rankings can be changed dynamically by the
> platform based on the workload and platform conditions and
> accounting for thermals and aging.
> When this occurs, cpu priority need to be set.
> 
> Signed-off-by: Meng Li <li.meng@....com>
> ---
>  drivers/cpufreq/amd-pstate.c | 32 ++++++++++++++++++++++++++++++++
>  include/linux/amd-pstate.h   |  1 +
>  2 files changed, 33 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index d02305675f66..8a8e4ecb1b5c 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -315,6 +315,7 @@ static int pstate_init_perf(struct amd_cpudata *cpudata)
>  	WRITE_ONCE(cpudata->nominal_perf, AMD_CPPC_NOMINAL_PERF(cap1));
>  	WRITE_ONCE(cpudata->lowest_nonlinear_perf, AMD_CPPC_LOWNONLIN_PERF(cap1));
>  	WRITE_ONCE(cpudata->lowest_perf, AMD_CPPC_LOWEST_PERF(cap1));
> +	WRITE_ONCE(cpudata->prefcore_highest_perf, AMD_CPPC_HIGHEST_PERF(cap1));
>  
>  	return 0;
>  }
> @@ -336,6 +337,7 @@ static int cppc_init_perf(struct amd_cpudata *cpudata)
>  	WRITE_ONCE(cpudata->lowest_nonlinear_perf,
>  		   cppc_perf.lowest_nonlinear_perf);
>  	WRITE_ONCE(cpudata->lowest_perf, cppc_perf.lowest_perf);
> +	WRITE_ONCE(cpudata->prefcore_highest_perf, cppc_perf.highest_perf);
>  
>  	if (cppc_state == AMD_PSTATE_ACTIVE)
>  		return 0;
> @@ -744,6 +746,34 @@ static void amd_pstate_init_prefcore(void)
>  	schedule_work(&sched_prefcore_work);
>  }
>  
> +static void amd_pstate_update_highest_perf(unsigned int cpu)
> +{
> +	struct cpufreq_policy *policy;
> +	struct amd_cpudata *cpudata;
> +	u32 prev_high = 0, cur_high = 0;
> +	u64 highest_perf;
> +	int ret;
> +
> +	if (!prefcore)
> +		return;
> +
> +	ret = amd_pstate_get_highest_perf(cpu, &highest_perf);
> +	if (ret)
> +		return;
> +
> +	policy = cpufreq_cpu_get(cpu);
> +	cpudata = policy->driver_data;
> +	cur_high = highest_perf;
> +	prev_high = READ_ONCE(cpudata->prefcore_highest_perf);
> +
> +	if (prev_high != cur_high) {
> +		WRITE_ONCE(cpudata->prefcore_highest_perf, cur_high);
> +		sched_set_itmt_core_prio(cur_high, cpu);
> +	}
> +
> +	cpufreq_cpu_put(policy);
> +}
> +
>  static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>  {
>  	int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> @@ -1468,6 +1498,7 @@ static struct cpufreq_driver amd_pstate_driver = {
>  	.suspend	= amd_pstate_cpu_suspend,
>  	.resume		= amd_pstate_cpu_resume,
>  	.set_boost	= amd_pstate_set_boost,
> +	.update_highest_perf	= amd_pstate_update_highest_perf,
>  	.name		= "amd-pstate",
>  	.attr		= amd_pstate_attr,
>  };
> @@ -1482,6 +1513,7 @@ static struct cpufreq_driver amd_pstate_epp_driver = {
>  	.online		= amd_pstate_epp_cpu_online,
>  	.suspend	= amd_pstate_epp_suspend,
>  	.resume		= amd_pstate_epp_resume,
> +	.update_highest_perf	= amd_pstate_update_highest_perf,
>  	.name		= "amd-pstate-epp",
>  	.attr		= amd_pstate_epp_attr,

If we intend to use the existing `update_limits` callback then this
patch needed to update. Otherwise looks good to me.

Reviewed-by: Wyes Karny <wyes.karny@....com>

>  };
> diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> index 446394f84606..fa86bc953d3e 100644
> --- a/include/linux/amd-pstate.h
> +++ b/include/linux/amd-pstate.h
> @@ -70,6 +70,7 @@ struct amd_cpudata {
>  	u32	nominal_perf;
>  	u32	lowest_nonlinear_perf;
>  	u32	lowest_perf;
> +	u32     prefcore_highest_perf;
>  
>  	u32	max_freq;
>  	u32	min_freq;
> -- 
> 2.34.1
>