nearly 100% graphics pipe of Rx570 usage when using certain applications

[Duncan]

René J.V. Bertin posted on Sun, 03 Jul 2022 12:21:03 +0200 as excerpted:


> Some thoughts for the OP:
> - does the issue persist if you log in under a non-Qt DE - xfce would be
> a good, lightweight choice?

Good idea but he tried that, saying fluxbox (X wm) didn't help.  And he 
tried X and wayland.

One thing he did /not/ mention trying was a different wayland compositor, 
like the weston I have as a backup here (it's reasonably barebones and not 
too complex, like fluxbox for X I guess), but given the above I doubt 
it'll change the situation.

> - see if you can identify a "pure Qt" application, ideally one that come
> with Qt (ideally the Assistant, Linguist, etc) which shows the issue.
> Then, install the same Qt version from Qt's own binaries, and as long as
> the issue reproduces with install older versions. In short, try to
> identify if this is some kind of regression in Qt. Qt's Creator would be
> a good candidate for testing except they only ship a build that uses the
> latest Qt version.

Good idea!  Along similar lines, try something like the vlc qt interface 
(the GUI default).  Again, try under kwin (wayland and x11 if possible), 
and under something else like weston for wayland and fluxbox for X.

BTW (@ the OP), how long has this been happening, and was it definitely 
*not* happening at some time in the past, or did you only recently try 
kde/plasma and thus don't know what the past status was?

It'd be /nice/ to know if say qt 5.14 or 5.10 or whatever didn't have the 
problem, while all of qt 5.15 (5.15.0-5.15.5, the latest available on at 
least gentoo) does.  That's a bit much to ask directly, but if if it could 
be said to have started around say the beginning of this year, or the 
beginning of last, and that it did work without the problems before that, 
that'd give some idea, certainly combined with the fact that arch tends to 
be reasonably current with its packages, which could then be time-synced 
to when the problem seemed to have begun.

> - the Intel driver (or at least the i915 one) has a number of parameters
> you can set at boot or, presumably, before launching the graphic
> environment. There is a lot of information out there on what parameter
> settings to use in case of specific performance or stability problems.
> Have you looked into those?

The amdgpu (and radeon) driver(s) don't emphasize such parameters as much 
as the intel driver does.  They generally try to do good defaults that I 
(and I suppose most non-gamers at least) have never bothered changing.  
There's also amdgpu/radeon configuration for xorg.conf that I used to 
tweak, but wayland's more difficult in that regard.

But there are indeed some kernel module parameters available.  A quick 
check of the kernel documentation pointed me at drivers/gpu/drm/amd/
amdgpu/amdgpu_drv.c, which is a C file but the one that processes the 
module parameters, so it lists them there.  AFAIK they'd be added to the 
kernel commandline as amdgpu.whatever=value.  Also see /sys/module/amdgpu/
parameters/*, where at least some may be run-time adjustable.

But at least here I've never touched any of that, tho I've updated radeon 
cards several times over the years as well as switching from radeon to 
amdgpu with one of those upgrades, agp to pcie with a mobo and gpu card 
change at some point before that, etc.

> - a bit of a long shot: have you tried different kernels? Newer (or
> older!!) ones, or a home-build with, say, the ConKolivas patches, or a
> Liquorix kernel?

Another good idea.  Given the graphics are old enough to have had support 
for awhile, I'd try at least a couple of the LTS kernels as well as the 
latest couple releases.

> NB: Qt does seem to be the culprit here; if I had to point fingers I'd
> look at the WebEngine and QML components which both have their own
> graphic engines.

FWIW I only had one app using qtwebengine (qtwebkit in the qt4 era), and 
decided at some point it simply wasn't worth it given the long qtwebengine 
build times (gentoo, remember, I cheat and do firefox-bin for a browser, 
but there's no qtwebengine-bin package to do the same with it) on my aging 
hardware.  Maybe next year with my computer upgrade, especially if I 
splurge and go whole-hog with the ~$10K 64-core/128-thread/256-gig 
threadripper system I'd like, but the ~$4K 16-core/32-thread/64-gig ryzen 
that's more realistic would at least make building qtwebengine and firefox 
(and chromium if I choose to) /reasonable/ again.

So no qtwebengine-requiring stuff installed here.  But dolphin at least 
doesn't require qtwebengine as I have dolphin installed.  And he said it 
was a problem.

But the qml components (qtdeclarative, and maybe qtquickcontrols and 
qtquickcontrols2?) I certainly still have, as they're both not as 
intensive to build and required by more of plasma/frameworks.  

But dolphin doesn't appear to require them either, and it was a problem...

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman