On Mon, 27 Dec 2021 18:54:41 +0100
Antony Stone <Antony.Stone@???> wrote:

> Hi.
>
> Disclaimer: I generally don't like people saying things like "I read
> somewhere that..." without backing up what they're talking about,
> but...
>
> I'm sure I've read somewhere (and not especially recently) that Linux
> on AMD Ryzen CPUs can be unreliable and/or surprisingly poor
> performance.
>
> Can anyone comment on current (eg: Beowulf / Chimaera with standard
> kernels) operation on such machines?

TL:DR =No. My problems seemed to all be with FX CPU and older hardware
and I'm finding no problems with the three models(3. 5 & 7) that I am
currently running,


I/We run eight (8) ASUS mobos + AMD CPU (2xFX & Ryzen 3x3, 2x5 & 1x7).
All but one run under Devuan.

The quick summary of what I remember of Debian, then Devuan pdrformance;

     Jessie; bad and would halt a system. I think these were all FX
     cpus and other ancient hardware.

     Beowulf; okay, but from time to time there would be copious
     messages in dmesg. Again, I think this was only the FX CPU and
     older hardware.

     Chimaera; seems to be 'fixed', very rare kernel line in dmesg. All
     old hardware has gone. My systems are now all ASUS Mobo with 2xFX
     and 6 times Ryzen.

Problems seemed to be associated with desktops uses, rather than one
purpose servers(web, mail, ftp, storage). May also have been related to
heavy demands as AMD support for their recent/leading(?) GPUS under
Linux is consistently bad and unreliable.
>
> If it matters, I'm looking at desktop / tower / server motherboards
> and not laptops, and I don't care two hoots about graphics - this
> would be for networked machines accessed exclusively remotely.
>
> Any opinions from personal experience, or pointers to reliable data,
> on the topic would be appreciated :)

I saw most problems on this hardware as it was my desktop/main machine
(highest load) then; 
     Mobo: ASUS Model ?? 
     CPU: AMD FX-8350 (8) @ 4.000GHz
     Memory: 483MiB / 15972MiB 

It also had problems under beowulf of handling software raid in a USB
external box in that it would spend hours on array maintenance. That
seems to have disappeared under Chimaera (nothing ion dmesg and no
usb/mdadm thrashing).

The only other problem system is with the mailer (Ryzen 3) dropping the
occassional logging entry. I only noticed this as I was watching for
email to arrive whilst solving a blocking problem and it didn't appear
in the log, but popped up on the desktop. Then again, this system is
also running a firewall. Although there isn't any indicators of load
any where as it all happens in ram, but dmesg is all FW logging.

System details;
Mobo: ASUS Prime 320M-K
CPU: AMD Ryzen 3 2200G (4) @ 3.500GHz

Also my main spinning rust storage which has no errors under dmesg
under Beowulf (time for upgrade)

     Mobo: ASUS  Prime B350-Plus 
     CPU: AMD A8-9600 RADEON R7 4C+6G (4) @ 3.100GHz 
     Memory: 143MiB / 3800MiB .

I wish I had purchased a couple more of these systems at the time.


So NO, I can not say there is a AMD Ryzen problem.

The other user is running on
     ASUS Prime A520-M
     CPU: AMD Ryzen 5 3600 (12) @ 3.600GHz
     GPU: AMD ATI Radeon R7 370 / R9 270X/370X
     Memory: 2916MiB / 15978MiB 
and the only dmesg entries relate to USB interaction with a Canon MFX
printer(TS9565) and their proprietary program (scangearmp2). The GPU
does not get any load.

YMMV, but when I purchased the two Ryzen 5 systems, there was
absolutely nothing with VEGA on it(built in graphics) which saves you
from having to buy a video card for the server.

Hope that helps.

Terry