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    SubjectRe: [PATCH V3 0/4] cpufreq: cppc: Add support for frequency invariance
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    On 6/25/2021 10:37 AM, Ionela Voinescu wrote:
    > Quick questions for you:
    >
    > 1. When you say you tried a 5.4 kernel, did you try it with these
    > patches backported? They also have some dependencies with the recent
    > changes in the arch topology driver and cpufreq so they would not be
    > straight forward to backport.
    >
    > If the 5.4 kernel you tried did not have these patches, it might be best
    > to try next/master that has these patches, but with
    > CONFIG_ACPI_CPPC_CPUFREQ_FIE=n, just to eliminate the possibility that
    > an incorrect frequency scale factor here would affect utilization that
    > would then affect the schedutil frequency selection. I would not expect
    > this behavior even if the scale factor was wrong, but it would be good
    > to rule out.
    >
    > 2. Is your platform booting with all CPUs? Are any hotplug operations
    > done in your scenario?

    Ionela, I found that set ACPI_PROCESSOR=y instead of ACPI_PROCESSOR=m will fix the previous mentioned issues here (any explanations of that?) even though the scaling down is not perfect. Now, we have the following on this idle system:

    # cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_cur_freq | sort | uniq -c
    79 1000000
    1 1160000
    73 1400000
    1 2000000
    4 2010000
    1 2800000
    1 860000

    Even if I rerun a few times, there could still have a few CPUs running lower than lowest_perf (1GHz). Also, even though I set all CPUs to use "userspace" governor and set freq to the lowest. A few CPUs keep changing at will.

    # cat /sys/devices/system/cpu/*/cpufreq/cpuinfo_cur_freq | sort | uniq -c
    156 1000000
    3 2000000
    1 760000

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