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Re: AMD EPYC throttled to 400 mhz




Am 17.01.22 um 11:36 schrieb Alexander V. Makartsev:
> On 17.01.2022 14:41, Simon Kainz wrote:
>> Hello,
>>
>> we are experiencing spontaneous CPU speed throttlings.
>>
>> System is a Lenovo  ThinkSystem SR645 with 2
>> AMD EPYC 7452 32-Core Processor, running
>>
>> Linux node3 5.10.0-10-amd64 #1 SMP Debian 5.10.84-1 (2021-12-08) x86_64
>> GNU/Linux
>>
>> After some time (hours, day, weeks even) the system suddenly gets
>> throttled to 400 Mhz (see below)
>>
>> HW Vendor replies with "Debian ist not on the supported OS" list, so we
>> are currently fighting on our own.
>>
>> Does someone else experince the same/similar issue? It seems to my as
>> some kind of thermal throttling, but kernel does not log thottling
>> events. Maybe some Debian-specific kernel setting, that influences CPU
>> throttling..
>>
> Are you sure it is not due to a "power save" feature for a system under
> low load?

Good point, but no, because the system is under heavy load all the time,
not idling.
After throttling down to 400 mhz, system also stays at this speed. Only
system reboot mitigates the issue.

> What CPU driver and Governor currently in use?
> https://www.kernel.org/doc/html/latest/admin-guide/pm/working-state.html

#CPU driver:

root@node3:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_driver
acpi-cpufreq

#Governor:
root@node3:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
schedutil

I did not set/change governor/driver settings, this is a stock debian
kernel.
> 
> Is the CPU temperature ok?
> Since this is a server platform, it could be due to wrong installation
> of FANs/Radiators/Air ducts and shields/etc.> Check it with "sensors".
yes, good point, but CPU/temp/fans are all ok. BMC, ipmi and management
interface all show no issues whatsovers.

Regards,

Simon


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