Re: [PATCH] Revert "cpufreq: intel_pstate: Fix ->set_policy() interface for no_turbo"

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

On Mon, 2018-08-06 at 23:50 +0200, Gabriele Mazzotta wrote:
> On 06/08/2018 18:49, Srinivas Pandruvada wrote:
> > On Mon, 2018-08-06 at 10:30 +0200, Rafael J. Wysocki wrote:
> > > On Sat, Aug 4, 2018 at 7:31 PM, Gabriele Mazzotta
> > > <gabriele.mzt@gmail.com> wrote:
> > > > On 04/08/2018 17:29, Gabriele Mazzotta wrote:
> > > > > This change does not take into account that some BIOSes
> > > > > change
> > > > > MSR_IA32_MISC_ENABLE_TURBO_DISABLE depending on the power
> > > > > source.
> > > > > If the turbo is disabled when the system boots,
> > > > > policy.max_freq
> > > > > is set to pstate.max_pstate. However, if the BIOS later
> > > > > enables
> > > > > the turbo, the CPU will never be able to run at
> > > > > pstate.turbo_pstate.
> > > > > 
> > > > > Since now intel_pstate_set_policy() does its calculations
> > > > > using
> > > > > pstate.max_freq and pstate.turbo_freq, we can always
> > > > > calculate
> > > > > cpuinfo.max_freq using pstate.turbo_pstate, thus allowing
> > > > > system
> > > > > with varying MSR_IA32_MISC_ENABLE_TURBO_DISABLE to run at
> > > > > full
> > > > > speed when the turbo is enabled.
> > > 
> > > Well, the problem with this approach is that always using
> > > pstate.turbo_pstate as the max causes the governor to
> > > overestimate
> > > the
> > > target frequency when the turbo range is not available (the
> > > target
> > > depends on the width of the entire available P-state range
> > > including
> > > turbo, so if the turbo range is not available, the number take
> > > into
> > > that computation is too large).
> > > 
> > > Are we expected to get notified when the BIOS updates
> > > MSR_IA32_MISC_ENABLE_TURBO_DISABLE?
> > 
> > Let's try this:
> > - boot with kernel command line 
> > 
> > intel_pstate=support_acpi_ppc dyndbg="file processor_perflib.c +p"
> > dyndbg="file intel_pstate.c +p"
> 
Interesting output.
Can you run ?
# turbostat --debug 
in both plugged and unplugged state.

Also output of acpidump?


> Plugged -> Unplugged:
> 
> [   40.046116] CPU 0: _PPC is 6 - frequency  limited
> [   40.046128] intel_pstate: policy->max > max non turbo frequency
> [   40.046131] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 3000000
> [   40.046134] intel_pstate: cpu:0 max_state 30 min_policy_perf:8
> max_policy_perf:30
> [   40.046137] intel_pstate: cpu:0 global_min:8 global_max:30
> [   40.046140] intel_pstate: cpu:0 max_perf_ratio:30 min_perf_ratio:8
> [   40.162173] CPU 0: _PPC is 6 - frequency  limited
> [   40.162186] intel_pstate: policy->max > max non turbo frequency
> [   40.162190] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 3000000
> [   40.162194] intel_pstate: cpu:0 max_state 30 min_policy_perf:8
> max_policy_perf:30
> [   40.162197] intel_pstate: cpu:0 global_min:8 global_max:30
> [   40.162200] intel_pstate: cpu:0 max_perf_ratio:30 min_perf_ratio:8
> [   40.162215] CPU 0: _PPC is 6 - frequency  limited
> [   40.162220] intel_pstate: policy->max > max non turbo frequency
> [   40.162223] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 3000000
> [   40.162226] intel_pstate: cpu:0 max_state 30 min_policy_perf:8
> max_policy_perf:30
> [   40.162228] intel_pstate: cpu:0 global_min:8 global_max:30
> [   40.162230] intel_pstate: cpu:0 max_perf_ratio:30 min_perf_ratio:8
> [   40.162237] CPU 0: _PPC is 6 - frequency  limited
> [   40.162241] intel_pstate: policy->max > max non turbo frequency
> [   40.162243] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 3000000
> [   40.162245] intel_pstate: cpu:0 max_state 30 min_policy_perf:8
> max_policy_perf:30
> [   40.162247] intel_pstate: cpu:0 global_min:8 global_max:30
> [   40.162249] intel_pstate: cpu:0 max_perf_ratio:30 min_perf_ratio:8
> [   40.162257] CPU 0: _PPC is 6 - frequency  limited
> [   40.162261] intel_pstate: policy->max > max non turbo frequency
> [   40.162263] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 3000000
> [   40.162265] intel_pstate: cpu:0 max_state 30 min_policy_perf:8
> max_policy_perf:30
> [   40.162267] intel_pstate: cpu:0 global_min:8 global_max:30
> [   40.162269] intel_pstate: cpu:0 max_perf_ratio:30 min_perf_ratio:8
> 
> Unplugged -> Plugged:
> 
> [   52.648535] CPU 0: _PPC is 6 - frequency  limited
> [   52.648553] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 1700000
> [   52.648558] intel_pstate: cpu:0 max_state 17 min_policy_perf:8
> max_policy_perf:17
> [   52.648562] intel_pstate: cpu:0 global_min:8 global_max:30
> [   52.648566] intel_pstate: cpu:0 max_perf_ratio:17 min_perf_ratio:8
> [   52.648583] CPU 0: _PPC is 6 - frequency  limited
> [   52.648590] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 1700000
> [   52.648595] intel_pstate: cpu:0 max_state 17 min_policy_perf:8
> max_policy_perf:17
> [   52.648598] intel_pstate: cpu:0 global_min:8 global_max:30
> [   52.648602] intel_pstate: cpu:0 max_perf_ratio:17 min_perf_ratio:8
> [   52.656093] CPU 0: _PPC is 6 - frequency  limited
> [   52.656111] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 1700000
> [   52.656116] intel_pstate: cpu:0 max_state 17 min_policy_perf:8
> max_policy_perf:17
> [   52.656120] intel_pstate: cpu:0 global_min:8 global_max:30
> [   52.656123] intel_pstate: cpu:0 max_perf_ratio:17 min_perf_ratio:8
> [   52.775577] CPU 0: _PPC is 6 - frequency  limited
> [   52.775594] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 1700000
> [   52.775598] intel_pstate: cpu:0 max_state 17 min_policy_perf:8
> max_policy_perf:17
> [   52.775601] intel_pstate: cpu:0 global_min:8 global_max:30
> [   52.775604] intel_pstate: cpu:0 max_perf_ratio:17 min_perf_ratio:8
> [   53.028620] CPU 0: _PPC is 6 - frequency  limited
> [   53.028637] intel_pstate: set_policy cpuinfo.max 3000000 policy-
> >max 1700000
> [   53.028643] intel_pstate: cpu:0 max_state 17 min_policy_perf:8
> max_policy_perf:17
> [   53.028647] intel_pstate: cpu:0 global_min:8 global_max:30
> [   53.028651] intel_pstate: cpu:0 max_perf_ratio:17 min_perf_ratio:8
> 
> > and send dmesg after you change power sources.
> > 
> > - Also try with
> > intel_pstate=disable dyndbg="file processor_perflib.c +p"
> 
> Nothing gets printed with this one.
> 
> Thanks,
> Gabriele
> 
> > and send dmesg.
> > 
> > Thanks,
> > Srinivas
> > 
> >