RE: [PATCH v10 3/8] cpufreq: amd-pstate: Unify computation of {max,min,nominal,lowest_nonlinear}_freq

[Yuan, Perry]

[AMD Official Use Only - General]

> -----Original Message-----
> From: Huang, Ray <Ray.Huang@xxxxxxx>
> Sent: Monday, April 15, 2024 10:55 PM
> To: Yuan, Perry <Perry.Yuan@xxxxxxx>
> Cc: rafael.j.wysocki@xxxxxxxxx; Limonciello, Mario
> <Mario.Limonciello@xxxxxxx>; viresh.kumar@xxxxxxxxxx; Shenoy, Gautham
> Ranjal <gautham.shenoy@xxxxxxx>; Petkov, Borislav
> <Borislav.Petkov@xxxxxxx>; Deucher, Alexander
> <Alexander.Deucher@xxxxxxx>; Huang, Shimmer
> <Shimmer.Huang@xxxxxxx>; oleksandr@xxxxxxxxxxxxxx; Du, Xiaojian
> <Xiaojian.Du@xxxxxxx>; Meng, Li (Jassmine) <Li.Meng@xxxxxxx>; linux-
> pm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v10 3/8] cpufreq: amd-pstate: Unify computation of
> {max,min,nominal,lowest_nonlinear}_freq
>
> On Mon, Mar 25, 2024 at 11:03:23AM +0800, Yuan, Perry wrote:
> > Currently the amd_get_{min, max, nominal, lowest_nonlinear}_freq()
> > helpers computes the values of min_freq, max_freq, nominal_freq and
> > lowest_nominal_freq respectively afresh from cppc_get_perf_caps().
> > This is not necessary as there are fields in cpudata to cache these
> > values.
> >
> > To simplify this, add a single helper function named
> > amd_pstate_init_freq() which computes all these frequencies at once,
> > and caches it in cpudata.
> >
> > Use the cached values everywhere else in the code.
> >
> > Reviewed-by: Li Meng <li.meng@xxxxxxx>
> > Tested-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@xxxxxxx>
> > Co-developed-by: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>
> > Signed-off-by: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>
> > Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
>
> I am thinking patch 3 and 4 should be squeezed together, because they are all
> refining frequencies in cpudata. But I am fine if you want to continue keep
> them separately.

Yes,   we would like to keep changes in two patches,   then patches don't need to get review again in v11.
Thanks.

Perry.

>
> > ---
> >  drivers/cpufreq/amd-pstate.c | 126
> > ++++++++++++++++-------------------
> >  1 file changed, 59 insertions(+), 67 deletions(-)
> >
> > diff --git a/drivers/cpufreq/amd-pstate.c
> > b/drivers/cpufreq/amd-pstate.c index 2015c9fcc3c9..ba1baa6733e6
> 100644
> > --- a/drivers/cpufreq/amd-pstate.c
> > +++ b/drivers/cpufreq/amd-pstate.c
> > @@ -606,74 +606,22 @@ static void amd_pstate_adjust_perf(unsigned int
> > cpu,
> >
> >  static int amd_get_min_freq(struct amd_cpudata *cpudata)  {
> > -   struct cppc_perf_caps cppc_perf;
> > -
> > -   int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> > -   if (ret)
> > -           return ret;
> > -
> > -   /* Switch to khz */
> > -   return cppc_perf.lowest_freq * 1000;
> > +   return READ_ONCE(cpudata->min_freq);
> >  }
> >
> >  static int amd_get_max_freq(struct amd_cpudata *cpudata)  {
> > -   struct cppc_perf_caps cppc_perf;
> > -   u32 max_perf, max_freq, nominal_freq, nominal_perf;
> > -   u64 boost_ratio;
> > -
> > -   int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> > -   if (ret)
> > -           return ret;
> > -
> > -   nominal_freq = cppc_perf.nominal_freq;
> > -   nominal_perf = READ_ONCE(cpudata->nominal_perf);
> > -   max_perf = READ_ONCE(cpudata->highest_perf);
> > -
> > -   boost_ratio = div_u64(max_perf << SCHED_CAPACITY_SHIFT,
> > -                         nominal_perf);
> > -
> > -   max_freq = nominal_freq * boost_ratio >> SCHED_CAPACITY_SHIFT;
> > -
> > -   /* Switch to khz */
> > -   return max_freq * 1000;
> > +   return READ_ONCE(cpudata->max_freq);
> >  }
> >
> >  static int amd_get_nominal_freq(struct amd_cpudata *cpudata)  {
> > -   struct cppc_perf_caps cppc_perf;
> > -
> > -   int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> > -   if (ret)
> > -           return ret;
> > -
> > -   /* Switch to khz */
> > -   return cppc_perf.nominal_freq * 1000;
> > +   return READ_ONCE(cpudata->nominal_freq);
> >  }
> >
> >  static int amd_get_lowest_nonlinear_freq(struct amd_cpudata *cpudata)
> > {
> > -   struct cppc_perf_caps cppc_perf;
> > -   u32 lowest_nonlinear_freq, lowest_nonlinear_perf,
> > -       nominal_freq, nominal_perf;
> > -   u64 lowest_nonlinear_ratio;
> > -
> > -   int ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> > -   if (ret)
> > -           return ret;
> > -
> > -   nominal_freq = cppc_perf.nominal_freq;
> > -   nominal_perf = READ_ONCE(cpudata->nominal_perf);
> > -
> > -   lowest_nonlinear_perf = cppc_perf.lowest_nonlinear_perf;
> > -
> > -   lowest_nonlinear_ratio = div_u64(lowest_nonlinear_perf <<
> SCHED_CAPACITY_SHIFT,
> > -                                    nominal_perf);
> > -
> > -   lowest_nonlinear_freq = nominal_freq * lowest_nonlinear_ratio >>
> SCHED_CAPACITY_SHIFT;
> > -
> > -   /* Switch to khz */
> > -   return lowest_nonlinear_freq * 1000;
> > +   return READ_ONCE(cpudata->lowest_nonlinear_freq);
> >  }
> >
> >  static int amd_pstate_set_boost(struct cpufreq_policy *policy, int
> > state) @@ -828,6 +776,53 @@ static void
> amd_pstate_update_limits(unsigned int cpu)
> >     mutex_unlock(&amd_pstate_driver_lock);
> >  }
> >
> > +/**
> > + * amd_pstate_init_freq: Initialize the max_freq, min_freq,
> > + *                       nominal_freq and lowest_nonlinear_freq for
> > + *                       the @cpudata object.
> > + *
> > + *  Requires: highest_perf, lowest_perf, nominal_perf and
> > + *            lowest_nonlinear_perf members of @cpudata to be
> > + *            initialized.
> > + *
> > + *  Returns 0 on success, non-zero value on failure.
> > + */
> > +static int amd_pstate_init_freq(struct amd_cpudata *cpudata) {
> > +   int ret;
> > +   u32 min_freq;
> > +   u32 highest_perf, max_freq;
> > +   u32 nominal_perf, nominal_freq;
> > +   u32 lowest_nonlinear_perf, lowest_nonlinear_freq;
> > +   u32 boost_ratio, lowest_nonlinear_ratio;
> > +   struct cppc_perf_caps cppc_perf;
> > +
> > +
> > +   ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
> > +   if (ret)
> > +           return ret;
> > +
> > +   min_freq = cppc_perf.lowest_freq * 1000;
> > +   nominal_freq = cppc_perf.nominal_freq * 1000;
> > +   nominal_perf = READ_ONCE(cpudata->nominal_perf);
> > +
> > +   highest_perf = READ_ONCE(cpudata->highest_perf);
> > +   boost_ratio = div_u64(highest_perf << SCHED_CAPACITY_SHIFT,
> nominal_perf);
> > +   max_freq = nominal_freq * boost_ratio >> SCHED_CAPACITY_SHIFT;
> > +
> > +   lowest_nonlinear_perf = READ_ONCE(cpudata-
> >lowest_nonlinear_perf);
> > +   lowest_nonlinear_ratio = div_u64(lowest_nonlinear_perf <<
> SCHED_CAPACITY_SHIFT,
> > +                                    nominal_perf);
> > +   lowest_nonlinear_freq = nominal_freq * lowest_nonlinear_ratio >>
> > +SCHED_CAPACITY_SHIFT;
> > +
> > +   WRITE_ONCE(cpudata->min_freq, min_freq);
> > +   WRITE_ONCE(cpudata->lowest_nonlinear_freq,
> lowest_nonlinear_freq);
> > +   WRITE_ONCE(cpudata->nominal_freq, nominal_freq);
> > +   WRITE_ONCE(cpudata->max_freq, max_freq);
> > +
> > +   return 0;
> > +}
> > +
> >  static int amd_pstate_cpu_init(struct cpufreq_policy *policy)  {
> >     int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> @@
> > -855,6 +850,10 @@ static int amd_pstate_cpu_init(struct cpufreq_policy
> *policy)
> >     if (ret)
> >             goto free_cpudata1;
> >
> > +   ret = amd_pstate_init_freq(cpudata);
> > +   if (ret)
> > +           goto free_cpudata1;
> > +
> >     min_freq = amd_get_min_freq(cpudata);
> >     max_freq = amd_get_max_freq(cpudata);
> >     nominal_freq = amd_get_nominal_freq(cpudata); @@ -896,13
> +895,8 @@
> > static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
> >             goto free_cpudata2;
> >     }
> >
> > -   /* Initial processor data capability frequencies */
> > -   cpudata->max_freq = max_freq;
> > -   cpudata->min_freq = min_freq;
> >     cpudata->max_limit_freq = max_freq;
> >     cpudata->min_limit_freq = min_freq;
> > -   cpudata->nominal_freq = nominal_freq;
> > -   cpudata->lowest_nonlinear_freq = lowest_nonlinear_freq;
> >
> >     policy->driver_data = cpudata;
> >
> > @@ -1317,6 +1311,10 @@ static int amd_pstate_epp_cpu_init(struct
> cpufreq_policy *policy)
> >     if (ret)
> >             goto free_cpudata1;
> >
> > +   ret = amd_pstate_init_freq(cpudata);
> > +   if (ret)
> > +           goto free_cpudata1;
> > +
> >     min_freq = amd_get_min_freq(cpudata);
> >     max_freq = amd_get_max_freq(cpudata);
> >     nominal_freq = amd_get_nominal_freq(cpudata); @@ -1333,12
> +1331,6 @@
> > static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> >     /* It will be updated by governor */
> >     policy->cur = policy->cpuinfo.min_freq;
> >
> > -   /* Initial processor data capability frequencies */
> > -   cpudata->max_freq = max_freq;
> > -   cpudata->min_freq = min_freq;
> > -   cpudata->nominal_freq = nominal_freq;
> > -   cpudata->lowest_nonlinear_freq = lowest_nonlinear_freq;
> > -
> >     policy->driver_data = cpudata;
> >
> >     cpudata->epp_cached = amd_pstate_get_epp(cpudata, 0);
> > --
> > 2.34.1
> >