[PATCH 07/12] cpufreq: amd_pstate: map desired perf into pstate scope for powersave governor

[PATCH 07/12] cpufreq: amd_pstate: map desired perf into pstate scope for powersave governor

[Perry Yuan]

The patch will fix the invalid desired perf value for powersave
governor. This issue is found when testing on one AMD EPYC system, the
actual des_perf is smaller than the min_perf value, that is invalid
value. because the min_perf is the lowest_perf system can support in
idle state.

Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
---
 drivers/cpufreq/amd-pstate.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 7c51f4125263..154eed849f38 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -317,6 +317,7 @@ static int amd_pstate_target(struct cpufreq_policy *policy,
 	des_perf = DIV_ROUND_CLOSEST(target_freq * cap_perf,
 				     cpudata->max_freq);
 
+	des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
 	cpufreq_freq_transition_begin(policy, &freqs);
 	amd_pstate_update(cpudata, min_perf, des_perf,
 			  max_perf, false);
-- 
2.25.1

Re: [PATCH 07/12] cpufreq: amd_pstate: map desired perf into pstate scope for powersave governor

[Nathan Fontenot]

On 7/7/22 12:00, Perry Yuan wrote:
> The patch will fix the invalid desired perf value for powersave
> governor. This issue is found when testing on one AMD EPYC system, the
> actual des_perf is smaller than the min_perf value, that is invalid
> value. because the min_perf is the lowest_perf system can support in
> idle state.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> ---
>  drivers/cpufreq/amd-pstate.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 7c51f4125263..154eed849f38 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -317,6 +317,7 @@ static int amd_pstate_target(struct cpufreq_policy *policy,
>  	des_perf = DIV_ROUND_CLOSEST(target_freq * cap_perf,
>  				     cpudata->max_freq);
>  
> +	des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
>  	cpufreq_freq_transition_begin(policy, &freqs);
>  	amd_pstate_update(cpudata, min_perf, des_perf,
>  			  max_perf, false);

The clamping of the desired perf value should be moved to amd_pstate_update(). The
only other caller of amd_pstate_update() is amd_pstate_adjust_perf() which already
clamps the desired perf value before making the call.

-Nathan

RE: [PATCH 07/12] cpufreq: amd_pstate: map desired perf into pstate scope for powersave governor

[Yuan, Perry]

[AMD Official Use Only - General]

Hi Nathan:

> -----Original Message-----
> From: Fontenot, Nathan <Nathan.Fontenot@amd.com>
> Sent: Friday, July 8, 2022 3:57 AM
> To: Yuan, Perry <Perry.Yuan@amd.com>; rafael.j.wysocki@intel.com;
> viresh.kumar@linaro.org; Huang, Ray <Ray.Huang@amd.com>; Rafael J.
> Wysocki <rafael@kernel.org>; linux-pm@vger.kernel.org; linux-
> kernel@vger.kernel.org
> Cc: Sharma, Deepak <Deepak.Sharma@amd.com>; Limonciello, Mario
> <Mario.Limonciello@amd.com>; Fontenot, Nathan
> <Nathan.Fontenot@amd.com>; Deucher, Alexander
> <Alexander.Deucher@amd.com>; Su, Jinzhou (Joe) <Jinzhou.Su@amd.com>;
> Huang, Shimmer <Shimmer.Huang@amd.com>; Du, Xiaojian
> <Xiaojian.Du@amd.com>; Meng, Li (Jassmine) <Li.Meng@amd.com>
> Subject: Re: [PATCH 07/12] cpufreq: amd_pstate: map desired perf into
> pstate scope for powersave governor
> 
> On 7/7/22 12:00, Perry Yuan wrote:
> > The patch will fix the invalid desired perf value for powersave
> > governor. This issue is found when testing on one AMD EPYC system, the
> > actual des_perf is smaller than the min_perf value, that is invalid
> > value. because the min_perf is the lowest_perf system can support in
> > idle state.
> >
> > Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
> > ---
> >  drivers/cpufreq/amd-pstate.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index 7c51f4125263..154eed849f38
> 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -317,6 +317,7 @@ static int amd_pstate_target(struct cpufreq_policy
> *policy,
> >  	des_perf = DIV_ROUND_CLOSEST(target_freq * cap_perf,
> >  				     cpudata->max_freq);
> >
> > +	des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
> >  	cpufreq_freq_transition_begin(policy, &freqs);
> >  	amd_pstate_update(cpudata, min_perf, des_perf,
> >  			  max_perf, false);
> 
> The clamping of the desired perf value should be moved to
> amd_pstate_update(). The only other caller of amd_pstate_update() is
> amd_pstate_adjust_perf() which already clamps the desired perf value
> before making the call.
> 
> -Nathan

Thanks for your suggestion.
Add this change into V2.

Perry.