[Bug 86461] New: intel_pstate does not obey min/max frequencies set by user

[Bug 86461] New: intel_pstate does not obey min/max frequencies set by user

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=86461

            Bug ID: 86461
           Summary: intel_pstate does not obey min/max frequencies set by
                    user
           Product: Power Management
           Version: 2.5
    Kernel Version: 3.17-rc5
          Hardware: All
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: cpufreq
          Assignee: cpufreq@vger.kernel.org
          Reporter: patrakov@gmail.com
        Regression: No

# uname -a    
Linux aep-vaio 3.17.0-rc5 #1 SMP PREEMPT Thu Sep 18 23:13:08 YEKT 2014 x86_64
Intel(R) Core(TM) i7-2640M CPU @ 2.80GHz GenuineIntel GNU/Linu

# echo 2400000 | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq

# cpufreq-info
cpufrequtils 008: cpufreq-info (C) Dominik Brodowski 2004-2009
Report errors and bugs to cpufreq@vger.kernel.org, please.
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 3.50 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 2.40 GHz and 3.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 804 MHz (asserted by call to hardware).
analyzing CPU 1:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 1
  CPUs which need to have their frequency coordinated by software: 1
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 3.50 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 2.40 GHz and 3.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 885 MHz (asserted by call to hardware).
analyzing CPU 2:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 2
  CPUs which need to have their frequency coordinated by software: 2
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 3.50 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 2.40 GHz and 3.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 800 MHz (asserted by call to hardware).
analyzing CPU 3:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 3
  CPUs which need to have their frequency coordinated by software: 3
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 3.50 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 2.40 GHz and 3.50 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 822 MHz (asserted by call to hardware).


As you see, my attempt to force the minimum frequency to 2.4 GHz has been
ignored.

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[Bug 86461] intel_pstate does not obey min/max frequencies set by user

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=86461

Dirk Brandewie <dirk.brandewie@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dirk.brandewie@gmail.com

--- Comment #1 from Dirk Brandewie <dirk.brandewie@gmail.com> ---
Can you send the output of the following commands before and after setting
scaling_min_freq:

   turbostat sleep 5
   grep MH /proc/cpuinfo
   grep .  /sys/devices/system/cpu/intel_pstate/*

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[Bug 86461] intel_pstate does not obey min/max frequencies set by user

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https://bugzilla.kernel.org/show_bug.cgi?id=86461

--- Comment #2 from Alexander E. Patrakov <patrakov@gmail.com> ---
aep-vaio turbostat # ./turbostat sleep 5
    Core     CPU Avg_MHz   %Busy Bzy_MHz TSC_MHz     SMI  CPU%c1  CPU%c3 
CPU%c6  CPU%c7 CoreTmp  PkgTmp Pkg%pc2 Pkg%pc3 Pkg%pc6 Pkg%pc7 PkgWatt CorWatt
GFXWatt 
       -       -      32    2.47    1298    2794       0    5.02    0.04   
0.00   92.47      50      50    3.79    0.02    4.49   77.75    4.43    0.74   
0.45
       0       0      37    2.97    1253    2794       0    6.90    0.07   
0.00   90.06      50      50    3.79    0.02    4.49   77.75    4.43    0.74   
0.45
       0       1      33    2.11    1558    2794       0    7.77
       1       2      27    3.05     895    2794       0    2.06    0.00   
0.00   94.89      50
       1       3      31    1.76    1763    2794       0    3.35
5.004419 sec
aep-vaio turbostat # grep MH /proc/cpuinfo
cpu MHz         : 951.781
cpu MHz         : 835.625
cpu MHz         : 852.468
cpu MHz         : 822.500
aep-vaio turbostat # grep .  /sys/devices/system/cpu/intel_pstate/*
/sys/devices/system/cpu/intel_pstate/max_perf_pct:100
/sys/devices/system/cpu/intel_pstate/min_perf_pct:22
/sys/devices/system/cpu/intel_pstate/no_turbo:0
aep-vaio turbostat # echo 2400000 | tee
/sys/devices/system/cpu/cpu*/cpufreq/scaling_min_freq
2400000
aep-vaio turbostat # ./turbostat sleep 5
    Core     CPU Avg_MHz   %Busy Bzy_MHz TSC_MHz     SMI  CPU%c1  CPU%c3 
CPU%c6  CPU%c7 CoreTmp  PkgTmp Pkg%pc2 Pkg%pc3 Pkg%pc6 Pkg%pc7 PkgWatt CorWatt
GFXWatt 
       -       -      39    1.74    2229    2794       0    4.47    0.51   
0.00   93.27      53      53    4.40    0.23    5.35   77.63    4.48    0.87   
0.37
       0       0      48    2.42    1981    2794       0    2.50    0.61   
0.00   94.47      53      53    4.40    0.23    5.35   77.63    4.48    0.87   
0.37
       0       1      13    0.78    1727    2794       0    4.14
       1       2      45    1.84    2420    2794       0    5.66    0.42   
0.00   92.08      53
       1       3      50    1.93    2560    2794       0    5.57
5.001705 sec
aep-vaio turbostat # grep MH /proc/cpuinfo
cpu MHz         : 1277.390
cpu MHz         : 1711.718
cpu MHz         : 1661.734
cpu MHz         : 1932.875
aep-vaio turbostat # grep .  /sys/devices/system/cpu/intel_pstate/*
/sys/devices/system/cpu/intel_pstate/max_perf_pct:100
/sys/devices/system/cpu/intel_pstate/min_perf_pct:68
/sys/devices/system/cpu/intel_pstate/no_turbo:0

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[Bug 86461] intel_pstate does not obey min/max frequencies set by user

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https://bugzilla.kernel.org/show_bug.cgi?id=86461

--- Comment #3 from Alexander E. Patrakov <patrakov@gmail.com> ---
Additional note: intel_pstate allows to set max_perf_pct lower than
min_perf_pct. This should not be allowed.

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[Bug 86461] intel_pstate does not obey min/max frequencies set by user

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=86461

--- Comment #4 from Dirk Brandewie <dirk.brandewie@gmail.com> ---
I looks like everything is working correctly.  You have to remember that the 
frequencies returned by turbostat and intel_pstate are measured effective
frequency over the time of the sample.  Previously with acpi_cpufreq the value
returned through /proc/cpuinfo and the cupfreq sysfs interface was the
requested
frequency and not the actual frequency.

If you want to see that the floor for P states has actually changed you can see 
the requested P state with:
  rdmsr -a -f15:8 0x199

The actual frequency that all cores on the processor run at is selected by the
processor based on the requests for all cores.

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[Bug 86461] intel_pstate does not obey min/max frequencies set by user

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=86461

--- Comment #5 from Alexander E. Patrakov <patrakov@gmail.com> ---
OK, the floor for the P states has indeed changed. If that MSR value
corresponds to the CPU frequency in units of 100 MHz, then the value is indeed
the desired one, and the bug can be closed as invalid.

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[Bug 86461] intel_pstate does not obey min/max frequencies set by user

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=86461

Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |alan@lxorguk.ukuu.org.uk
         Resolution|---                         |INVALID

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[Bug 86461] intel_pstate does not obey min/max frequencies set by user

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=86461

Len Brown <lenb@kernel.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED
                 CC|                            |lenb@kernel.org

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