linux-kernel - Re: [PATCH v7 08/13] cpufreq: amd-pstate: add frequency dynamic boost sysfs control

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Date:   Mon, 12 Dec 2022 18:14:58 +0800
From:   Huang Rui <ray.huang@....com>
To:     "Yuan, Perry" <Perry.Yuan@....com>
Cc:     "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
        "Limonciello, Mario" <Mario.Limonciello@....com>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
        "Sharma, Deepak" <Deepak.Sharma@....com>,
        "Fontenot, Nathan" <Nathan.Fontenot@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Huang, Shimmer" <Shimmer.Huang@....com>,
        "Du, Xiaojian" <Xiaojian.Du@....com>,
        "Meng, Li (Jassmine)" <Li.Meng@....com>,
        "Karny, Wyes" <Wyes.Karny@....com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 08/13] cpufreq: amd-pstate: add frequency dynamic
 boost sysfs control

On Thu, Dec 08, 2022 at 07:18:47PM +0800, Yuan, Perry wrote:
> From: Perry Yuan <Perry.Yuan@....com>
> 
> Add one sysfs entry to control the CPU cores frequency boost state
> The attribute file can allow user to set max performance boosted or
> keeping at normal perf level.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> ---
>  drivers/cpufreq/amd-pstate.c | 67 ++++++++++++++++++++++++++++++++++--
>  1 file changed, 65 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index ea9255bdc9ac..4cd53c010215 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -69,6 +69,7 @@ static struct amd_pstate_params global_params;
>  
>  static DEFINE_MUTEX(amd_pstate_limits_lock);
>  static DEFINE_MUTEX(amd_pstate_driver_lock);
> +struct kobject *amd_pstate_kobj;
>  
>  static bool cppc_boost __read_mostly;
>  
> @@ -768,12 +769,46 @@ static ssize_t show_energy_performance_preference(
>  	return sysfs_emit(buf, "%s\n", energy_perf_strings[preference]);
>  }
>  
> +static void amd_pstate_update_policies(void)
> +{
> +	int cpu;
> +
> +	for_each_possible_cpu(cpu)
> +		cpufreq_update_policy(cpu);
> +}
> +
> +static ssize_t show_cppc_dynamic_boost(struct kobject *kobj,
> +				struct kobj_attribute *attr, char *buf)
> +{
> +	return sysfs_emit(buf, "%u\n", cppc_boost);
> +}
> +
> +static ssize_t store_cppc_dynamic_boost(struct kobject *a,
> +				       struct kobj_attribute *b,
> +				       const char *buf, size_t count)
> +{
> +	bool new_state;
> +	int ret;
> +
> +	ret = kstrtobool(buf, &new_state);
> +	if (ret)
> +		return -EINVAL;
> +
> +	mutex_lock(&amd_pstate_driver_lock);
> +	cppc_boost = !!new_state;
> +	amd_pstate_update_policies();
> +	mutex_unlock(&amd_pstate_driver_lock);

This patch should wait that after we confirm the iowait boost necessity for
amd-pstate.

Thanks,
Ray

> +
> +	return count;
> +}
> +
>  cpufreq_freq_attr_ro(amd_pstate_max_freq);
>  cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
>  
>  cpufreq_freq_attr_ro(amd_pstate_highest_perf);
>  cpufreq_freq_attr_rw(energy_performance_preference);
>  cpufreq_freq_attr_ro(energy_performance_available_preferences);
> +define_one_global_rw(cppc_dynamic_boost);
>  
>  static struct freq_attr *amd_pstate_attr[] = {
>  	&amd_pstate_max_freq,
> @@ -791,6 +826,15 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
>  	NULL,
>  };
>  
> +static struct attribute *pstate_global_attributes[] = {
> +	&cppc_dynamic_boost.attr,
> +	NULL
> +};
> +
> +static const struct attribute_group amd_pstate_global_attr_group = {
> +	.attrs = pstate_global_attributes,
> +};
> +
>  static inline void update_boost_state(void)
>  {
>  	u64 misc_en;
> @@ -1404,9 +1448,28 @@ static int __init amd_pstate_init(void)
>  
>  	ret = cpufreq_register_driver(default_pstate_driver);
>  	if (ret)
> -		pr_err("failed to register amd pstate driver with return %d\n",
> -		       ret);
> +		pr_err("failed to register driver with return %d\n", ret);
> +
> +	amd_pstate_kobj = kobject_create_and_add("amd-pstate", &cpu_subsys.dev_root->kobj);
> +	if (!amd_pstate_kobj) {
> +		ret = -EINVAL;
> +		pr_err("global sysfs registration failed.\n");
> +		goto kobject_free;
> +	}
> +
> +	ret = sysfs_create_group(amd_pstate_kobj, &amd_pstate_global_attr_group);
> +	if (ret) {
> +		pr_err("sysfs attribute export failed with error %d.\n", ret);
> +		goto global_attr_free;
> +	}
> +
> +	return ret;
>  
> +global_attr_free:
> +	kobject_put(amd_pstate_kobj);
> +kobject_free:
> +	cpufreq_unregister_driver(default_pstate_driver);
> +	kfree(cpudata);
>  	return ret;
>  }
>  device_initcall(amd_pstate_init);
> -- 
> 2.34.1
>