Re: 37afb0003242 ("cpufreq: intel_pstate: Use ACPI perf configuration") makes intel_pstate kaputt

From: Rafael J. Wysocki
Date: Tue Nov 17 2015 - 09:09:30 EST


On Tuesday, November 17, 2015 10:09:47 AM Borislav Petkov wrote:
> Hi,
>
> patch in $Subject breaks my IVB laptop here. It does not go over 1.2GHz
> during load like building a kernel with -j4, for example. 1.2GHz
> according to cpupower in tools/power/cpupower is the lowest P-state:
>
> # LD_LIBRARY_PATH=. ./cpupower frequency-info
> 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: 1.20 GHz - 3.60 GHz
> available cpufreq governors: performance, powersave
> current policy: frequency should be within 1.20 GHz and 3.60 GHz.
> The governor "powersave" may decide which speed to use
> within this range.
> current CPU frequency is 1.20 GHz (asserted by call to hardware).
> boost state support:
> Supported: yes
> Active: yes
> 3400 MHz max turbo 4 active cores
> 3400 MHz max turbo 3 active cores
> 3400 MHz max turbo 2 active cores
> 3600 MHz max turbo 1 active cores
> ---
>
> turbostat output during building a kernel is:
>
> CPU Avg_MHz %Busy Bzy_MHz TSC_MHz
> - 1194 99.70 1200 2893
> 0 1196 99.92 1200 2893
> 1 1197 99.97 1200 2893
> 2 1197 99.95 1200 2893
> 3 1185 98.95 1200 2893
>
> I've enabled the pr_debug's in intel_pstate_init_perf_limits() and it
> says:
>
> [ 0.826111] intel_pstate: default limits 0xc 0x1d 0x24
> [ 0.829252] intel_pstate: CPU0 - ACPI _PSS perf data
> [ 0.830337] intel_pstate: Updated limits using _PSS 0xc 0x1d 0x24
> [ 0.830356] intel_pstate: policy max_freq=3600000 Khz min_freq = 1200000 KHz
> [ 0.830908] intel_pstate: default limits 0xc 0x1d 0x24
> [ 0.833002] intel_pstate: CPU1 - ACPI _PSS perf data
> [ 0.833339] intel_pstate: Updated limits using _PSS 0xc 0x1d 0x24
> [ 0.833361] intel_pstate: policy max_freq=3600000 Khz min_freq = 1200000 KHz
> [ 0.833535] intel_pstate: default limits 0xc 0x1d 0x24
> [ 0.835727] intel_pstate: CPU2 - ACPI _PSS perf data
> [ 0.836036] intel_pstate: Updated limits using _PSS 0xc 0x1d 0x24
> [ 0.836058] intel_pstate: policy max_freq=3600000 Khz min_freq = 1200000 KHz
> [ 0.836237] intel_pstate: default limits 0xc 0x1d 0x24
> [ 0.838432] intel_pstate: CPU3 - ACPI _PSS perf data
> [ 0.838731] intel_pstate: Updated limits using _PSS 0xc 0x1d 0x24
> [ 0.838753] intel_pstate: policy max_freq=3600000 Khz min_freq = 1200000 KHz
>
> during boot.
>
> When I boot with "intel_pstate=no_acpi" it boosts normally to 3.4GHz and
> above and turbostat says:
>
> CPU Avg_MHz %Busy Bzy_MHz TSC_MHz
> - 3392 99.92 3400 2895
> 0 3395 99.96 3400 2897
> 1 3390 99.88 3400 2895
> 2 3391 99.89 3400 2895
> 3 3391 99.95 3400 2893
>
> which is what it should be saying. :)

Well, sorry for the breakage.

acpidump output would help to diagnose this I suppose.

Thanks,
Rafael

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