Re: [PATCH v6 3/6] cpufreq: amd_pstate: Add guided autonomous mode

[Wyes Karny <wyes.karny@amd.com>]

On 16 Feb 14:08, Huang Rui wrote:
> On Tue, Feb 07, 2023 at 01:21:54AM +0800, Karny, Wyes wrote:
> > From ACPI spec below 3 modes for CPPC can be defined:
> > 1. Non autonomous: OS scaling governor specifies operating frequency/
> >    performance level through `Desired Performance` register and platform
> > follows that.
> > 2. Guided autonomous: OS scaling governor specifies min and max
> >    frequencies/ performance levels through `Minimum Performance` and
> > `Maximum Performance` register, and platform can autonomously select an
> > operating frequency in this range.
> 
> I believe the processors which are not sensitive to power consumption can
> use this mode. Because this way can have better performance than "non
> autonomous" mode. :-)
> 
> > 3. Fully autonomous: OS only hints (via EPP) to platform for the required
> >    energy performance preference for the workload and platform autonomously
> > scales the frequency.
> > 
> > Currently (1) is supported by amd_pstate as passive mode, and (3) is
> > implemented by EPP support. This change is to support (2).
> > 
> > In guided autonomous mode the min_perf is based on the input from the
> > scaling governor. For example, in case of schedutil this value depends
> > on the current utilization. And max_perf is set to max capacity.
> > 
> > To activate guided auto mode ``amd_pstate=guided`` command line
> > parameter has to be passed in the kernel.
> > 
> > Signed-off-by: Wyes Karny <wyes.karny@amd.com>
> > Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> 
> Wyes, could you still use prefix "cpufreq: amd-pstate:" as the subject to
> align the previous patches? Because it's easy to sort out all amd-pstate
> patches for us.

Sure, will do.

Thanks,
Wyes
> 
> Acked-by: Huang Rui <ray.huang@amd.com>
> 
> > ---
> >  .../admin-guide/kernel-parameters.txt         | 15 +++++---
> >  drivers/cpufreq/amd-pstate.c                  | 34 +++++++++++++++----
> >  include/linux/amd-pstate.h                    |  2 ++
> >  3 files changed, 40 insertions(+), 11 deletions(-)
> > 
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index e3618dfdb36a..56d5c189e458 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -7015,11 +7015,11 @@
> >  			  Do not enable amd_pstate as the default
> >  			  scaling driver for the supported processors
> >  			passive
> > -			  Use amd_pstate as a scaling driver, driver requests a
> > -			  desired performance on this abstract scale and the power
> > -			  management firmware translates the requests into actual
> > -			  hardware states (core frequency, data fabric and memory
> > -			  clocks etc.)
> > +			  Use amd_pstate with passive mode as a scaling driver.
> > +			  In this mode autonomous selection is disabled.
> > +			  Driver requests a desired performance level and platform
> > +			  tries to match the same performance level if it is
> > +			  satisfied by guaranteed performance level.
> >  			active
> >  			  Use amd_pstate_epp driver instance as the scaling driver,
> >  			  driver provides a hint to the hardware if software wants
> > @@ -7027,3 +7027,8 @@
> >  			  to the CPPC firmware. then CPPC power algorithm will
> >  			  calculate the runtime workload and adjust the realtime cores
> >  			  frequency.
> > +			guided
> > +			  Activate guided autonomous mode. Driver requests minimum and
> > +			  maximum performance level and the platform autonomously
> > +			  selects a performance level in this range and appropriate
> > +			  to the current workload.
> > diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> > index 168a28bed6ee..6582c922ad3a 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -308,7 +308,22 @@ static int cppc_init_perf(struct amd_cpudata *cpudata)
> >  		   cppc_perf.lowest_nonlinear_perf);
> >  	WRITE_ONCE(cpudata->lowest_perf, cppc_perf.lowest_perf);
> >  
> > -	return 0;
> > +	if (cppc_state == AMD_PSTATE_ACTIVE)
> > +		return 0;
> > +
> > +	ret = cppc_get_auto_sel_caps(cpudata->cpu, &cppc_perf);
> > +	if (ret) {
> > +		pr_warn("failed to get auto_sel, ret: %d\n", ret);
> > +		return 0;
> > +	}
> > +
> > +	ret = cppc_set_auto_sel(cpudata->cpu,
> > +			(cppc_state == AMD_PSTATE_PASSIVE) ? 0 : 1);
> > +
> > +	if (ret)
> > +		pr_warn("failed to set auto_sel, ret: %d\n", ret);
> > +
> > +	return ret;
> >  }
> >  
> >  DEFINE_STATIC_CALL(amd_pstate_init_perf, pstate_init_perf);
> > @@ -385,12 +400,18 @@ static inline bool amd_pstate_sample(struct amd_cpudata *cpudata)
> >  }
> >  
> >  static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
> > -			      u32 des_perf, u32 max_perf, bool fast_switch)
> > +			      u32 des_perf, u32 max_perf, bool fast_switch, int gov_flags)
> >  {
> >  	u64 prev = READ_ONCE(cpudata->cppc_req_cached);
> >  	u64 value = prev;
> >  
> >  	des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
> > +
> > +	if ((cppc_state == AMD_PSTATE_GUIDED) && (gov_flags & CPUFREQ_GOV_DYNAMIC_SWITCHING)) {
> > +		min_perf = des_perf;
> > +		des_perf = 0;
> > +	}
> > +
> >  	value &= ~AMD_CPPC_MIN_PERF(~0L);
> >  	value |= AMD_CPPC_MIN_PERF(min_perf);
> >  
> > @@ -445,7 +466,7 @@ static int amd_pstate_target(struct cpufreq_policy *policy,
> >  
> >  	cpufreq_freq_transition_begin(policy, &freqs);
> >  	amd_pstate_update(cpudata, min_perf, des_perf,
> > -			  max_perf, false);
> > +			  max_perf, false, policy->governor->flags);
> >  	cpufreq_freq_transition_end(policy, &freqs, false);
> >  
> >  	return 0;
> > @@ -479,7 +500,8 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
> >  	if (max_perf < min_perf)
> >  		max_perf = min_perf;
> >  
> > -	amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true);
> > +	amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true,
> > +			policy->governor->flags);
> >  	cpufreq_cpu_put(policy);
> >  }
> >  
> > @@ -1279,7 +1301,7 @@ static int __init amd_pstate_init(void)
> >  	/* capability check */
> >  	if (boot_cpu_has(X86_FEATURE_CPPC)) {
> >  		pr_debug("AMD CPPC MSR based functionality is supported\n");
> > -		if (cppc_state == AMD_PSTATE_PASSIVE)
> > +		if (cppc_state != AMD_PSTATE_ACTIVE)
> >  			current_pstate_driver->adjust_perf = amd_pstate_adjust_perf;
> >  	} else {
> >  		pr_debug("AMD CPPC shared memory based functionality is supported\n");
> > @@ -1341,7 +1363,7 @@ static int __init amd_pstate_param(char *str)
> >  		if (cppc_state == AMD_PSTATE_ACTIVE)
> >  			current_pstate_driver = &amd_pstate_epp_driver;
> >  
> > -		if (cppc_state == AMD_PSTATE_PASSIVE)
> > +		if (cppc_state == AMD_PSTATE_PASSIVE || cppc_state == AMD_PSTATE_GUIDED)
> >  			current_pstate_driver = &amd_pstate_driver;
> >  
> >  		return 0;
> > diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
> > index f5f22418e64b..c10ebf8c42e6 100644
> > --- a/include/linux/amd-pstate.h
> > +++ b/include/linux/amd-pstate.h
> > @@ -97,6 +97,7 @@ enum amd_pstate_mode {
> >  	AMD_PSTATE_DISABLE = 0,
> >  	AMD_PSTATE_PASSIVE,
> >  	AMD_PSTATE_ACTIVE,
> > +	AMD_PSTATE_GUIDED,
> >  	AMD_PSTATE_MAX,
> >  };
> >  
> > @@ -104,6 +105,7 @@ static const char * const amd_pstate_mode_string[] = {
> >  	[AMD_PSTATE_DISABLE]     = "disable",
> >  	[AMD_PSTATE_PASSIVE]     = "passive",
> >  	[AMD_PSTATE_ACTIVE]      = "active",
> > +	[AMD_PSTATE_GUIDED]      = "guided",
> >  	NULL,
> >  };
> >  #endif /* _LINUX_AMD_PSTATE_H */
> > -- 
> > 2.34.1
> >