Re: [PATCH V2 1/4] cpufreq: amd-pstate: Add more tracepoint for AMD P-State module

[Huang Rui <ray.huang@amd.com>]

On Wed, Mar 09, 2022 at 09:23:38AM +0800, Su, Jinzhou (Joe) wrote:
> [AMD Official Use Only]
> 
> > -----Original Message-----
> > From: Huang, Ray <Ray.Huang@amd.com>
> > Sent: Friday, March 4, 2022 2:42 PM
> > To: Su, Jinzhou (Joe) <Jinzhou.Su@amd.com>
> > Cc: rjw@rjwysocki.net; linux-pm@vger.kernel.org;
> > srinivas.pandruvada@linux.intel.com; dsmythies@telus.net;
> > viresh.kumar@linaro.org; todd.e.brandt@linux.intel.com; linux-
> > kernel@vger.kernel.org; Sharma, Deepak <Deepak.Sharma@amd.com>;
> > Deucher, Alexander <Alexander.Deucher@amd.com>; Du, Xiaojian
> > <Xiaojian.Du@amd.com>; Yuan, Perry <Perry.Yuan@amd.com>; Meng, Li
> > (Jassmine) <Li.Meng@amd.com>
> > Subject: Re: [PATCH V2 1/4] cpufreq: amd-pstate: Add more tracepoint for
> > AMD P-State module
> >
> > On Fri, Mar 04, 2022 at 02:07:21PM +0800, Su, Jinzhou (Joe) wrote:
> > > Add frequency, mperf, aperf and tsc in the trace. This can be used to
> > > debug and tune the performance of AMD P-state driver.
> > >
> > > Use the time difference between amd_pstate_update to calculate CPU
> > > frequency. There could be sleep in arch_freq_get_on_cpu, so do not use
> > > it here.
> > >
> > > Signed-off-by: Jinzhou Su <Jinzhou.Su@amd.com>
> > > Co-developed-by: Huang Rui <ray.huang@amd.com>
> > > Signed-off-by: Huang Rui <ray.huang@amd.com>
> >
> > Let's remove "Signed-off-by" of me, just leave "Co-developed-by".
> >
> > > ---
> > >  drivers/cpufreq/amd-pstate-trace.h | 22 ++++++++++-
> > >  drivers/cpufreq/amd-pstate.c       | 59 +++++++++++++++++++++++++++++-
> > >  2 files changed, 78 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/cpufreq/amd-pstate-trace.h
> > > b/drivers/cpufreq/amd-pstate-trace.h
> > > index 647505957d4f..35f38ae67fb1 100644
> > > --- a/drivers/cpufreq/amd-pstate-trace.h
> > > +++ b/drivers/cpufreq/amd-pstate-trace.h
> > > @@ -27,6 +27,10 @@ TRACE_EVENT(amd_pstate_perf,
> > >     TP_PROTO(unsigned long min_perf,
> > >              unsigned long target_perf,
> > >              unsigned long capacity,
> > > +            u64 freq,
> > > +            u64 mperf,
> > > +            u64 aperf,
> > > +            u64 tsc,
> > >              unsigned int cpu_id,
> > >              bool changed,
> > >              bool fast_switch
> > > @@ -35,6 +39,10 @@ TRACE_EVENT(amd_pstate_perf,
> > >     TP_ARGS(min_perf,
> > >             target_perf,
> > >             capacity,
> > > +           freq,
> > > +           mperf,
> > > +           aperf,
> > > +           tsc,
> > >             cpu_id,
> > >             changed,
> > >             fast_switch
> > > @@ -44,6 +52,10 @@ TRACE_EVENT(amd_pstate_perf,
> > >             __field(unsigned long, min_perf)
> > >             __field(unsigned long, target_perf)
> > >             __field(unsigned long, capacity)
> > > +           __field(unsigned long long, freq)
> > > +           __field(unsigned long long, mperf)
> > > +           __field(unsigned long long, aperf)
> > > +           __field(unsigned long long, tsc)
> > >             __field(unsigned int, cpu_id)
> > >             __field(bool, changed)
> > >             __field(bool, fast_switch)
> > > @@ -53,15 +65,23 @@ TRACE_EVENT(amd_pstate_perf,
> > >             __entry->min_perf = min_perf;
> > >             __entry->target_perf = target_perf;
> > >             __entry->capacity = capacity;
> > > +           __entry->freq = freq;
> > > +           __entry->mperf = mperf;
> > > +           __entry->aperf = aperf;
> > > +           __entry->tsc = tsc;
> > >             __entry->cpu_id = cpu_id;
> > >             __entry->changed = changed;
> > >             __entry->fast_switch = fast_switch;
> > >             ),
> > >
> > > -   TP_printk("amd_min_perf=%lu amd_des_perf=%lu
> > amd_max_perf=%lu cpu_id=%u changed=%s fast_switch=%s",
> > > +   TP_printk("amd_min_perf=%lu amd_des_perf=%lu
> > amd_max_perf=%lu
> > > +freq=%llu mperf=%llu aperf=%llu tsc=%llu cpu_id=%u changed=%s
> > > +fast_switch=%s",
> > >               (unsigned long)__entry->min_perf,
> > >               (unsigned long)__entry->target_perf,
> > >               (unsigned long)__entry->capacity,
> > > +             (unsigned long long)__entry->freq,
> > > +             (unsigned long long)__entry->mperf,
> > > +             (unsigned long long)__entry->aperf,
> > > +             (unsigned long long)__entry->tsc,
> > >               (unsigned int)__entry->cpu_id,
> > >               (__entry->changed) ? "true" : "false",
> > >               (__entry->fast_switch) ? "true" : "false"
> > > diff --git a/drivers/cpufreq/amd-pstate.c
> > > b/drivers/cpufreq/amd-pstate.c index 9ce75ed11f8e..7be38bc6a673 100644
> > > --- a/drivers/cpufreq/amd-pstate.c
> > > +++ b/drivers/cpufreq/amd-pstate.c
> > > @@ -65,6 +65,18 @@ MODULE_PARM_DESC(shared_mem,
> > >
> > >  static struct cpufreq_driver amd_pstate_driver;
> > >
> > > +/**
> > > + * struct  amd_aperf_mperf
> > > + * @aperf: actual performance frequency clock count
> > > + * @mperf: maximum performance frequency clock count
> > > + * @tsc:   time stamp counter
> > > + */
> > > +struct amd_aperf_mperf {
> > > +   u64 aperf;
> > > +   u64 mperf;
> > > +   u64 tsc;
> > > +};
> > > +
> > >  /**
> > >   * struct amd_cpudata - private CPU data for AMD P-State
> > >   * @cpu: CPU number
> > > @@ -81,6 +93,9 @@ static struct cpufreq_driver amd_pstate_driver;
> > >   * @min_freq: the frequency that mapped to lowest_perf
> > >   * @nominal_freq: the frequency that mapped to nominal_perf
> > >   * @lowest_nonlinear_freq: the frequency that mapped to
> > > lowest_nonlinear_perf
> > > + * @cur: Difference of Aperf/Mperf/tsc count between last and current
> > > + sample
> > > + * @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
> > >   *
> > >   * The amd_cpudata is key private data for each CPU thread in AMD
> > > P-State, and @@ -102,6 +117,10 @@ struct amd_cpudata {
> > >     u32     nominal_freq;
> > >     u32     lowest_nonlinear_freq;
> > >
> > > +   struct amd_aperf_mperf cur;
> > > +   struct amd_aperf_mperf prev;
> > > +
> > > +   u64 freq;
> > >     bool    boost_supported;
> > >  };
> > >
> > > @@ -211,6 +230,39 @@ static inline void amd_pstate_update_perf(struct
> > amd_cpudata *cpudata,
> > >                                         max_perf, fast_switch);
> > >  }
> > >
> > > +static inline bool amd_pstate_sample(struct amd_cpudata *cpudata) {
> > > +   u64 aperf, mperf, tsc;
> > > +   unsigned long flags;
> > > +
> > > +   local_irq_save(flags);
> > > +   rdmsrl(MSR_IA32_APERF, aperf);
> > > +   rdmsrl(MSR_IA32_MPERF, mperf);
> > > +   tsc = rdtsc();
> > > +
> > > +   if (cpudata->prev.mperf == mperf || cpudata->prev.tsc == tsc) {
> > > +           local_irq_restore(flags);
> > > +           return false;
> > > +   }
> > > +
> > > +   local_irq_restore(flags);
> > > +
> > > +   cpudata->cur.aperf = aperf;
> > > +   cpudata->cur.mperf = mperf;
> > > +   cpudata->cur.tsc =  tsc;
> > > +   cpudata->cur.aperf -= cpudata->prev.aperf;
> > > +   cpudata->cur.mperf -= cpudata->prev.mperf;
> > > +   cpudata->cur.tsc -= cpudata->prev.tsc;
> > > +
> > > +   cpudata->prev.aperf = aperf;
> > > +   cpudata->prev.mperf = mperf;
> > > +   cpudata->prev.tsc = tsc;
> > > +
> > > +   cpudata->freq = div64_u64((cpudata->cur.aperf * cpu_khz),
> > > +cpudata->cur.mperf);
> > > +
> > > +   return true;
> > > +}
> > > +
> > >  static void amd_pstate_update(struct amd_cpudata *cpudata, u32
> > min_perf,
> > >                           u32 des_perf, u32 max_perf, bool fast_switch)
> > { @@ -226,8
> > > +278,11 @@ static void amd_pstate_update(struct amd_cpudata *cpudata,
> > u32 min_perf,
> > >     value &= ~AMD_CPPC_MAX_PERF(~0L);
> > >     value |= AMD_CPPC_MAX_PERF(max_perf);
> > >
> > > -   trace_amd_pstate_perf(min_perf, des_perf, max_perf,
> > > -                         cpudata->cpu, (value != prev), fast_switch);
> > > +   if (trace_amd_pstate_perf_enabled() &&
> > amd_pstate_sample(cpudata)) {
> > > +           trace_amd_pstate_perf(min_perf, des_perf, max_perf,
> > cpudata->freq,
> > > +                   cpudata->cur.mperf, cpudata->cur.aperf, cpudata-
> > >cur.tsc,
> > > +                           cpudata->cpu, (value != prev), fast_switch);
> >
> > How about using struct amd_aperf_mperf pointer as one input:
> >
> > trace_amd_pstate_perf(min_perf, des_perf, max_perf, &cpudata->cur, ...);
> >
> > You can refer the members of struct amd_aperf_mperf in the
> > amd-pstate-trace.h:
> >
> >       __entry->mperf = cur->mperf;
> >       __entry->aperf = cur->aperf;
> >       __entry->tsc = cur->tsc;
> >
> 
> I prefer the former way. We'd better to split the definition of struct "amd_cpudata" into head file and include it in the trace file with your change. Will do that in the future if needed.
> 

Hmm, it should be ok. Because the trace implementation will be moved to
include/trace/events/power.h after the shared_mem is enabled.

Thanks,
Ray