Re: [intel-pstate driver regression] processor frequency very high even if in idle

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On Thu, 2016-03-31 at 19:27 +0200, Jörg Otte wrote:
> 2016-03-31 17:43 GMT+02:00 Rafael J. Wysocki <rjw@rjwysocki.net>:
> > On Thursday, March 31, 2016 05:25:18 PM Jörg Otte wrote:
> > > 2016-03-31 13:42 GMT+02:00 Rafael J. Wysocki <rjw@rjwysocki.net>:
> > > > On Thursday, March 31, 2016 11:05:56 AM Jörg Otte wrote:
> > > > 
> > > > [cut]
> > > > 
> > > > > > 
> > > > > 
> > > > > Yes, works for me.
> > > > > 
> > > > > CPUID(7): No-SGX
> > > > >      CPU Avg_MHz   Busy% Bzy_MHz TSC_MHz
> > > > >        -      11    0.66 1682 2494
> > > > >        0      11    0.60 1856 2494
> > > > >        1       6    0.34    1898    2494
> > > > >        2      13    0.82    1628    2494
> > > > >        3      13    0.87    1528    2494
> > > > >      CPU Avg_MHz   Busy% Bzy_MHz TSC_MHz
> > > > >        -       6    0.58     963    2494
> > > > >        0       8    0.83     957    2494
> > > > >        1       1    0.08     984    2494
> > > > >        2      10    1.04     975    2494
> > > > >        3       3    0.35     934    2494
> > > > > 
> > > > 
> > 
> > [cut]
> > 
> > > > 
> > > 
> > > No, this patch doesn't help.
> > 
> > Well, more work to do then.
> > 
> > I've just noticed a bug in this patch, which is not relevant for
> > the results,
> > but below is a new version.
> > 
> > > CPUID(7): No-SGX
> > >       CPU Avg_MHz   Busy% Bzy_MHz TSC_MHz
> > >        -       8    0.32    2507    2495
> > >        0      13    0.53    2505    2495
> > >        1       3    0.11    2523    2495
> > >        2       1    0.06    2555    2495
> > >        3      15    0.59    2500    2495
> > >      CPU Avg_MHz   Busy% Bzy_MHz TSC_MHz
> > >        -       8    0.33    2486    2495
> > >        0      12    0.50    2482    2495
> > >        1       5    0.22    2489    2495
> > >        2       1    0.04    2492    2495
> > >        3      15    0.59    2487    2495
> > 
> > Please apply the patch below and take a (1s or so) trace from the
> > pstate_sample
> > tracepoint (under /sys/kernel/debug/tracing/events/power/ on my
> > systems).
> > 
> > Then please apply the revert instead of it and take a trace from
> > that tracepoint
> > again and send both of the traces to me.
> > 
> > ---
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > Subject: [PATCH] intel_pstate: Do not set utilization update hook
> > too early
> > 
> > The utilization update hook in the intel_pstate driver is set too
> > early, as it only should be set after the policy has been fully
> > initialized by the core.  That may cause intel_pstate_update_util()
> > to use incorrect data and put the CPUs into incorrect P-states as
> > a result.
> > 
> > To prevent that from happening, make intel_pstate_set_policy() set
> > the utilization update hook instead of intel_pstate_init_cpu() so
> > intel_pstate_update_util() only runs when all things have been
> > initialized as appropriate.
> > 
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >  drivers/cpufreq/intel_pstate.c |   27 +++++++++++++++++++--------
> >  1 file changed, 19 insertions(+), 8 deletions(-)
> > 
> > Index: linux-pm/drivers/cpufreq/intel_pstate.c
> > ===================================================================
> > --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> > +++ linux-pm/drivers/cpufreq/intel_pstate.c
> > @@ -1103,7 +1103,6 @@ static int intel_pstate_init_cpu(unsigne
> >         intel_pstate_sample(cpu, 0);
> > 
> >         cpu->update_util.func = intel_pstate_update_util;
> > -       cpufreq_set_update_util_data(cpunum, &cpu->update_util);
> > 
> >         pr_debug("intel_pstate: controlling: cpu %d\n", cpunum);
> > 
> > @@ -1122,18 +1121,29 @@ static unsigned int intel_pstate_get(uns
> >         return get_avg_frequency(cpu);
> >  }
> > 
> > +static void intel_pstate_set_update_util_hook(unsigned int cpu)
> > +{
> > +       cpufreq_set_update_util_data(cpu, &all_cpu_data[cpu]-
> > >update_util);
> > +}
> > +
> > +static void intel_pstate_clear_update_util_hook(unsigned int cpu)
> > +{
> > +       cpufreq_set_update_util_data(cpu, NULL);
> > +       synchronize_sched();
> > +}
> > +
> >  static int intel_pstate_set_policy(struct cpufreq_policy *policy)
> >  {
> >         if (!policy->cpuinfo.max_freq)
> >                 return -ENODEV;
> > 
> > +       intel_pstate_clear_update_util_hook(policy->cpu);
> > +
> >         if (policy->policy == CPUFREQ_POLICY_PERFORMANCE &&
> >             policy->max >= policy->cpuinfo.max_freq) {
> >                 pr_debug("intel_pstate: set performance\n");
> >                 limits = &performance_limits;
> > -               if (hwp_active)
> > -                       intel_pstate_hwp_set(policy->cpus);
> > -               return 0;
> > +               goto out;
> >         }
> > 
> >         pr_debug("intel_pstate: set powersave\n");
> > @@ -1163,6 +1173,9 @@ static int intel_pstate_set_policy(struc
> >         limits->max_perf = div_fp(int_tofp(limits->max_perf_pct),
> >                                   int_tofp(100));
> > 
> > + out:
> > +       intel_pstate_set_update_util_hook(policy->cpu);
> > +
> >         if (hwp_active)
> >                 intel_pstate_hwp_set(policy->cpus);
> > 
> > @@ -1187,8 +1200,7 @@ static void intel_pstate_stop_cpu(struct
> > 
> >         pr_debug("intel_pstate: CPU %d exiting\n", cpu_num);
> > 
> > -       cpufreq_set_update_util_data(cpu_num, NULL);
> > -       synchronize_sched();
> > +       intel_pstate_clear_update_util_hook(cpu_num);
> > 
> >         if (hwp_active)
> >                 return;
> > @@ -1455,8 +1467,7 @@ out:
> >         get_online_cpus();
> >         for_each_online_cpu(cpu) {
> >                 if (all_cpu_data[cpu]) {
> > -                       cpufreq_set_update_util_data(cpu, NULL);
> > -                       synchronize_sched();
> > +                       intel_pstate_clear_update_util_hook(cpu);
> >                         kfree(all_cpu_data[cpu]);
> >                 }
> >         }
> > 
> 
> OK, patch is applied.
> After some configurations and compilations I'm there.
> Under pstate_sample I see:
> enable  filter  format  id  trigger
> 
> what to do now ? (never did tracing before)'

# cd /sys/kernel/debug/tracing/
# echo 1 > events/power/pstate_sample/enable
# echo 1 > events/power/cpu_frequency/enable
# cat trace
Send us the trace file.

Also your kernel config doesn't have many modules, Is it a custom
configuration you do for your system?

Thanks,
Srinivas

 
> 
> Thanks, Jörg