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

Yuan, Perry
2024-04-18T09:15:33Z

[AMD Official Use Only - General]

> -----Original Message-----
> From: Huang, Ray <Ray.Huang@amd.com>
> Sent: Monday, April 15, 2024 10:55 PM
> To: Yuan, Perry <Perry.Yuan@amd.com>
> Cc: rafael.j.wysocki@intel.com; Limonciello, Mario
> <Mario.Limonciello@amd.com>; viresh.kumar@linaro.org; Shenoy, Gautham
> Ranjal <gautham.shenoy@amd.com>; Petkov, Borislav
> <Borislav.Petkov@amd.com>; Deucher, Alexander
> <Alexander.Deucher@amd.com>; Huang, Shimmer
> <Shimmer.Huang@amd.com>; oleksandr@natalenko.name; Du, Xiaojian
> <Xiaojian.Du@amd.com>; Meng, Li (Jassmine) <Li.Meng@amd.com>; linux-
> pm@vger.kernel.org; linux-kernel@vger.kernel.org
> 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@amd.com>
> > Tested-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@amd.com>
> > Co-developed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
> > Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
> > Signed-off-by: Perry Yuan <perry.yuan@amd.com>
>
> 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
> >