RE: [PATCH V10 3/7] cpufreq: amd-pstate: Enable amd-pstate preferred core supporting.

From: Yuan, Perry
Date: Thu Nov 02 2023 - 05:05:43 EST

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[AMD Official Use Only - General]

Hi meng Li,

> -----Original Message-----
> From: Meng, Li (Jassmine) <Li.Meng@xxxxxxx>
> Sent: Monday, October 30, 2023 2:34 PM
> To: Rafael J . Wysocki <rafael.j.wysocki@xxxxxxxxx>; Huang, Ray
> <Ray.Huang@xxxxxxx>
> Cc: linux-pm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; x86@xxxxxxxxxx;
> linux-acpi@xxxxxxxxxxxxxxx; Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>; linux-
> kselftest@xxxxxxxxxxxxxxx; Fontenot, Nathan <Nathan.Fontenot@xxxxxxx>;
> Sharma, Deepak <Deepak.Sharma@xxxxxxx>; Deucher, Alexander
> <Alexander.Deucher@xxxxxxx>; Limonciello, Mario
> <Mario.Limonciello@xxxxxxx>; Huang, Shimmer
> <Shimmer.Huang@xxxxxxx>; Yuan, Perry <Perry.Yuan@xxxxxxx>; Du,
> Xiaojian <Xiaojian.Du@xxxxxxx>; Viresh Kumar <viresh.kumar@xxxxxxxxxx>;
> Borislav Petkov <bp@xxxxxxxxx>; Oleksandr Natalenko
> <oleksandr@xxxxxxxxxxxxxx>; Meng, Li (Jassmine) <Li.Meng@xxxxxxx>;
> Karny, Wyes <Wyes.Karny@xxxxxxx>
> Subject: [PATCH V10 3/7] cpufreq: amd-pstate: Enable amd-pstate preferred
> core supporting.
>
> amd-pstate driver utilizes the functions and data structures provided by the
> ITMT architecture to enable the scheduler to favor scheduling on cores which
> can be get a higher frequency with lower voltage. We call it amd-pstate
> preferrred core.
>
> Here sched_set_itmt_core_prio() is called to set priorities and
> sched_set_itmt_support() is called to enable ITMT feature.
> amd-pstate driver uses the highest performance value to indicate the priority
> of CPU. The higher value has a higher priority.
>
> The initial core rankings are set up by amd-pstate when the system boots.
>
> Add a variable hw_prefcore in cpudata structure. It will check if the processor
> and power firmware support preferred core feature.
>
> Add one new early parameter `disable` to allow user to disable the preferred
> core.
>
> Only when hardware supports preferred core and user set `enabled` in early
> parameter, amd pstate driver supports preferred core featue.
>
> Tested-by: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx>
> Reviewed-by: Huang Rui <ray.huang@xxxxxxx>
> Reviewed-by: Wyes Karny <wyes.karny@xxxxxxx>
> Reviewed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> Co-developed-by: Perry Yuan <Perry.Yuan@xxxxxxx>
> Signed-off-by: Perry Yuan <Perry.Yuan@xxxxxxx>
> Signed-off-by: Meng Li <li.meng@xxxxxxx>
> ---
> drivers/cpufreq/amd-pstate.c | 141
> +++++++++++++++++++++++++++++++----
> include/linux/amd-pstate.h | 4 +
> 2 files changed, 129 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 9a1e194d5cf8..2033e5e70017 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -37,6 +37,7 @@
> #include <linux/uaccess.h>
> #include <linux/static_call.h>
> #include <linux/amd-pstate.h>
> +#include <linux/topology.h>
>
> #include <acpi/processor.h>
> #include <acpi/cppc_acpi.h>
> @@ -49,6 +50,7 @@
>
> #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 @@ -64,6 +66,7 @@ static struct cpufreq_driver amd_pstate_driver;
> static struct cpufreq_driver amd_pstate_epp_driver; static int cppc_state =
> AMD_PSTATE_UNDEFINED; static bool cppc_enabled;
> +static bool amd_pstate_prefcore = true;
>
> /*
> * AMD Energy Preference Performance (EPP) @@ -290,23 +293,21 @@
> static inline int amd_pstate_enable(bool enable) static int
> pstate_init_perf(struct amd_cpudata *cpudata) {
> u64 cap1;
> - u32 highest_perf;
>
> int ret = rdmsrl_safe_on_cpu(cpudata->cpu, MSR_AMD_CPPC_CAP1,
> &cap1);
> if (ret)
> return ret;
>
> - /*
> - * TODO: Introduce AMD specific power feature.
> - *
> - * CPPC entry doesn't indicate the highest performance in some ASICs.
> + /* 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.
> */
> - 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);
> + if (cpudata->hw_prefcore)
> + WRITE_ONCE(cpudata->highest_perf,
> AMD_PSTATE_PREFCORE_THRESHOLD);
> + else
> + WRITE_ONCE(cpudata->highest_perf,
> AMD_CPPC_HIGHEST_PERF(cap1));
>
> WRITE_ONCE(cpudata->nominal_perf,
> AMD_CPPC_NOMINAL_PERF(cap1));
> WRITE_ONCE(cpudata->lowest_nonlinear_perf,
> AMD_CPPC_LOWNONLIN_PERF(cap1)); @@ -318,17 +319,15 @@ static int
> pstate_init_perf(struct amd_cpudata *cpudata) static int
> cppc_init_perf(struct amd_cpudata *cpudata) {
> struct cppc_perf_caps cppc_perf;
> - u32 highest_perf;
>
> int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> if (ret)
> return ret;
>
> - 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);
> + if (cpudata->hw_prefcore)
> + WRITE_ONCE(cpudata->highest_perf,
> AMD_PSTATE_PREFCORE_THRESHOLD);
> + else
> + WRITE_ONCE(cpudata->highest_perf,
> cppc_perf.highest_perf);
>
> WRITE_ONCE(cpudata->nominal_perf, cppc_perf.nominal_perf);
> WRITE_ONCE(cpudata->lowest_nonlinear_perf,
> @@ -676,6 +675,80 @@ static void amd_perf_ctl_reset(unsigned int cpu)
> wrmsrl_on_cpu(cpu, MSR_AMD_PERF_CTL, 0); }
>
> +/*
> + * Set amd-pstate preferred core enable can't be done directly from
> +cpufreq callbacks
> + * due to locking, so queue the work for later.
> + */
> +static void amd_pstste_sched_prefcore_workfn(struct work_struct *work)
> +{
> + sched_set_itmt_support();
> +}
> +static DECLARE_WORK(sched_prefcore_work,
> +amd_pstste_sched_prefcore_workfn);
> +
> +/*
> + * Get the highest performance register value.
> + * @cpu: CPU from which to get highest performance.
> + * @highest_perf: Return address.
> + *
> + * Return: 0 for success, -EIO otherwise.
> + */
> +static int amd_pstate_get_highest_perf(int cpu, u32 *highest_perf) {
> + int ret;
> +
> + if (boot_cpu_has(X86_FEATURE_CPPC)) {
> + u64 cap1;
> +
> + ret = rdmsrl_safe_on_cpu(cpu, MSR_AMD_CPPC_CAP1,
> &cap1);
> + if (ret)
> + return ret;
> + WRITE_ONCE(*highest_perf,
> AMD_CPPC_HIGHEST_PERF(cap1));
> + } else {
> + u64 cppc_highest_perf;
> +
> + ret = cppc_get_highest_perf(cpu, &cppc_highest_perf);
> + if (ret)
> + return ret;
> + WRITE_ONCE(*highest_perf, cppc_highest_perf);
> + }
> +
> + return (ret);
> +}
> +
> +#define CPPC_MAX_PERF U8_MAX
> +
> +static void amd_pstate_init_prefcore(struct amd_cpudata *cpudata) {
> + int ret, prio;
> + u32 highest_perf;
> +
> + ret = amd_pstate_get_highest_perf(cpudata->cpu, &highest_perf);
> + if (ret)
> + return;
> +
> + cpudata->hw_prefcore = true;
> + /* check if CPPC preferred core feature is enabled*/
> + if (highest_perf < CPPC_MAX_PERF)
> + prio = (int)highest_perf;
> + else {
> + pr_debug("AMD CPPC preferred core is unsupported!\n");
> + cpudata->hw_prefcore = false;
> + return;
> + }
> +
> + if (!amd_pstate_prefcore)
> + return;

Move the feature state check to earlier before you call amd_pstate_get_highest_perf().
If the feature is not enabled, you have no need to read highest perf.

> +
> + /*
> + * The priorities can be set regardless of whether or not
> + * sched_set_itmt_support(true) has been called and it is valid to
> + * update them at any time after it has been called.
> + */
> + sched_set_itmt_core_prio(prio, cpudata->cpu);
> +
> + schedule_work(&sched_prefcore_work);
> +}
> +
> static int amd_pstate_cpu_init(struct cpufreq_policy *policy) {
> int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> @@ -697,6 +770,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy
> *policy)
>
> cpudata->cpu = policy->cpu;
>
> + amd_pstate_init_prefcore(cpudata);
> +
> ret = amd_pstate_init_perf(cpudata);
> if (ret)
> goto free_cpudata1;
> @@ -845,6 +920,17 @@ static ssize_t show_amd_pstate_highest_perf(struct
> cpufreq_policy *policy,
> return sysfs_emit(buf, "%u\n", perf);
> }
>
> +static ssize_t show_amd_pstate_hw_prefcore(struct cpufreq_policy *policy,
> + char *buf)
> +{
> + bool hw_prefcore;
> + struct amd_cpudata *cpudata = policy->driver_data;
> +
> + hw_prefcore = READ_ONCE(cpudata->hw_prefcore);
> +
> + return sysfs_emit(buf, "%s\n", hw_prefcore ? "supported" :
> +"unsupported"); }

Replace the string with str_enabled_disabled() function that is defined as below.

include/linux/string_helpers.h

static inline const char *str_enabled_disabled(bool v)
{
return v ? "enabled" : "disabled";
}

Perry.

> +
> static ssize_t show_energy_performance_available_preferences(
> struct cpufreq_policy *policy, char *buf)
> { @@ -1037,18 +1123,27 @@ static ssize_t status_store(struct device *a,
> struct device_attribute *b,
> return ret < 0 ? ret : count;
> }
>
> +static ssize_t prefcore_show(struct device *dev,
> + struct device_attribute *attr, char *buf) {
> + return sysfs_emit(buf, "%s\n", amd_pstate_prefcore ? "enabled" :
> +"disabled"); }

Replace the string with str_enabled_disabled() function that is defined as below.

include/linux/string_helpers.h

> +
> 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_ro(amd_pstate_hw_prefcore);
> cpufreq_freq_attr_rw(energy_performance_preference);
> cpufreq_freq_attr_ro(energy_performance_available_preferences);
> static DEVICE_ATTR_RW(status);
> +static DEVICE_ATTR_RO(prefcore);
>
> static struct freq_attr *amd_pstate_attr[] = {
> &amd_pstate_max_freq,
> &amd_pstate_lowest_nonlinear_freq,
> &amd_pstate_highest_perf,
> + &amd_pstate_hw_prefcore,
> NULL,
> };
>
> @@ -1056,6 +1151,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
> &amd_pstate_max_freq,
> &amd_pstate_lowest_nonlinear_freq,
> &amd_pstate_highest_perf,
> + &amd_pstate_hw_prefcore,
> &energy_performance_preference,
> &energy_performance_available_preferences,
> NULL,
> @@ -1063,6 +1159,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
>
> static struct attribute *pstate_global_attributes[] = {
> &dev_attr_status.attr,
> + &dev_attr_prefcore.attr,
> NULL
> };
>
> @@ -1114,6 +1211,8 @@ static int amd_pstate_epp_cpu_init(struct
> cpufreq_policy *policy)
> cpudata->cpu = policy->cpu;
> cpudata->epp_policy = 0;
>
> + amd_pstate_init_prefcore(cpudata);
> +
> ret = amd_pstate_init_perf(cpudata);
> if (ret)
> goto free_cpudata1;
> @@ -1527,7 +1626,17 @@ static int __init amd_pstate_param(char *str)
>
> return amd_pstate_set_driver(mode_idx); }
> +
> +static int __init amd_prefcore_param(char *str) {
> + if (!strcmp(str, "disable"))
> + amd_pstate_prefcore = false;
> +
> + return 0;
> +}
> +
> early_param("amd_pstate", amd_pstate_param);
> +early_param("amd_prefcore", amd_prefcore_param);
>
> MODULE_AUTHOR("Huang Rui <ray.huang@xxxxxxx>");
> MODULE_DESCRIPTION("AMD Processor P-state Frequency Driver"); diff --git
> a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h index
> 446394f84606..87e140e9e6db 100644
> --- a/include/linux/amd-pstate.h
> +++ b/include/linux/amd-pstate.h
> @@ -52,6 +52,9 @@ struct amd_aperf_mperf {
> * @prev: Last Aperf/Mperf/tsc count value read from register
> * @freq: current cpu frequency value
> * @boost_supported: check whether the Processor or SBIOS supports boost
> mode
> + * @hw_prefcore: check whether HW supports preferred core featue.
> + * Only when hw_prefcore and early prefcore param are true,
> + * AMD P-State driver supports preferred core featue.
> * @epp_policy: Last saved policy used to set energy-performance preference
> * @epp_cached: Cached CPPC energy-performance preference value
> * @policy: Cpufreq policy value
> @@ -81,6 +84,7 @@ struct amd_cpudata {
>
> u64 freq;
> bool boost_supported;
> + bool hw_prefcore;
>
> /* EPP feature related attributes*/
> s16 epp_policy;
> --
> 2.34.1

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