Fw: FreebSD12 xorg with -AMDGPU- RADEON

[andrew glaeser]

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To tell you the truth, I had some more hassle with my computer, it turned out

in fact, that at 10°C lower air-temperature, at an average of 20°C, the

problem was basically the same, PCB-turbo is nonsense, just does not work

without throttling, no matter which frequency you set for it.

But it turned out, that powerd was the culprit, because of its default

strategy of adaptive-hi, so this had to be changed in order to avoid massive

throttling, and a maximum CPU-frequency of 2.3 GHz seems feasible now.

Base-frequency is 1.2 GHz (i.e. multiplier 12 in UEFI), and I have 1333

MHz memory-clock now.

So it is OK to enable CPU core-boost, but maximum CPU-frequency needs to be

limited by powerd:

> root at fbsd12:~ # cat /etc/rc.conf

.
..
> powerd_enable="YES"
> powerd_flags="-a adaptive -m 1200 -M 2300"
..
.

this way one gets a more dynamic system, avoiding to run at constant

CPU-frequency, while still avoiding irq-18 throttling and saving electrical

power.

The problem was new to me, because this PC used to run with debian-linux in

legacy mode, my other computers do too, to be honest, thermal throttling never

had been any issue so far.

Personally I do not have any problem with underclocking, but it is still

strange, that it is necessary, and it has some impact on system-performance,

but less impact than massive throttling.

Massive irq-18 throttling basically keeps the system usable while working

headless over SSH, but when sitting at the BSD-desktop, it accumulates to an

IRQ-storm, so newly opened windows, from GIMP for instance appear black, and

indeed you cannot continue with your work.
 
So, if you experience anything similar, then please think of

powerd-configuration, changing anything about ACPI-tables was not necessary

in my case, it also appears too complicated.



 

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Some more measures were taken:

* power-supply replaced with a more recent efficient one
* 8 cm, 5 V case-fan replaced with PWM-regulated 12 cm fan
* extra air-inlets drilled into the case-lid, does not really matter, if you
  have found the computer-case on the trash-yard, I know, kind of ridiculous,
  100% hand-made, even freehand drilled
* thermal grease renewed below CPU-cooler
* CPU-fan replaced with a more performant new fan

So, since all possible sources of failure have been ruled out, that irq-18
kept reappearing because of a too high surrounding air-temperature. We have
another heat-wave here in Berlin currently, today or tomorrow is the peak
around 35° C. This means irq-18 appears over 30°C temperature already at
boot-time and it will not go away, regardless of fan-configuration, unless
you lower CPU-core clock. This is a complex problem.
For instance today, about one hour ago I had to lower the CPU-clock to 1.7
GHz (with no core-boost) instead of the nominal 3.6 GHz in order to get rid
of irq-18 throttling. Obviously this has a severe impact on
system-performance, so next time, when I upgrade the system to current DDR4
RAM, I am going to go for a 35 W A-series APU, this box had 65 W of nominal
TDP, but without the graphics-card, with CPU-graphics only.




Begin forwarded message:

Date: Thu, 15 Aug 2019 13:23:12 +0200
From: andrew glaeser <bugs at irregulaire.info>
To: freebsd-x11 at freebsd.org, debian-x at lists.debian.org,
memberservices at amd-member.com Subject: Re: Fw: FreebSD12 xorg with -AMDGPU-
RADEON


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I struggled for some more days with system-stability with Radeon 6450 card:

* extra 8 cm case-fan installed, see jpg-attachment
* memory-frequency limited to 1300 (instead of 1600 MHz auto-mode),
* PCB-CPU-turbo disabled,
* AMD memory-profile enabled,
* finally # echo 'radeon.pcie_gen2="0"' >> /boot/loader.conf

I do hope I have a stable system now, see attached [dmesg.tx.xz]

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