Re: AMD EPYC throttled to 400 mhz

["Alexander V. Makartsev" <avbetev@gmail.com>]

On 17.01.2022 18:40, Simon Kainz wrote:

> 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 server platform runs latest BIOS and firmware?
    Things I'd try first if I was in your place.
    I always flash latest firmware available as a pre-sale procedure, or
    during server installation.
    
    I've also found this bug report¹ . Could be the same issue with
    scaling driver, which was fixed in kernel 5.11.
    Debian stable runs version 5.10.84, so test the system with newer
    kernel.
    
    
    ¹ https://bugzilla.kernel.org/show_bug.cgi?id=211305
-- 
With kindest regards, Alexander.

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