[Bug 234733] cpufreq: Setting CPU frequency with sysctl dev.cpu.0.fr slows a Ryzen 2700X down

From: <bugzilla-noreply_at_freebsd.org>
Date: Fri, 30 Jul 2021 02:24:17 UTC

Kubilay Kocak <koobs@FreeBSD.org> changed:

           What    |Removed                     |Added
           Assignee|bugs@FreeBSD.org            |cem@freebsd.org
            Summary|Setting CPU frequency with  |cpufreq: Setting CPU
                   |sysctl dev.cpu.0.fr slows a |frequency with sysctl
                   |Ryzen 2700X down            |dev.cpu.0.fr slows a Ryzen
                   |                            |2700X down
              Flags|                            |mfc-stable12?

--- Comment #26 from Kubilay Kocak <koobs@FreeBSD.org> ---
^Triage: Assign to committer that resolved


 IRC user reporting:

ASUS Pro WS 565-ACE motherboard (AMI BIOS) and AMD Ryzen 9 5950X 16-Core
Processor. I've installed 12.2/amd64 STABLE (GENERIC), it runs fine but I
cannot get Precision Boost 2 supported.

dev.cpu.0.freq_levels: 3400/3740 2800/2800 2200/1980

I expect 3401 in this list as sign of CPU Boost support, but it's not there

"acpidump -d" shows that "_PSS: Performance Supported States" is here in ACPI

There are also following errors in boot log but I doubt they have connection to
boost problems:

  acpi_wmi0: cannot find EC device
  device_attach: acpi_wmi0 attach returned 6

I've added "hint.apic.0.clock=0" to /boot/loader.conf and
"dev.cpu.0.cx_lowest=C2" to /etc/sysctl.conf and it enabled C2 state indeed,
but still no Boost.

I've pointed them here and asked them to apply the patch to their stable/12 to
reproduce/validate the fix (if this issue is indeed related).

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