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frugal technology, simple living and guerrilla large-appliance repair
Thu, 13 Nov 2014

Why OpenBSD runs so hot on AMD A4 APU hardware -- and how to cool it down 20 degrees C

The good news is that I can run X in OpenBSD 5.6 on my AMD A4 APU-equipped HP Pavilion g6 laptop. Before now, starting X would cause a kernel panic.

The bad news is that the laptop runs very, very hot.

This OpenBSD misc post explains it:


List:       openbsd-misc
Subject:    Re: Slow performance on Radeon (HD7770) video card
From:       Jonathan Gray 
Date:       2014-06-22 5:12:12
Message-ID: 20140622051212.GC9087 () mail ! netspace ! net ! au
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On Sat, Jun 21, 2014 at 10:32:55PM +0200, Julian Andrej wrote:
> Hello,
> 
> i'm getting really low performance on my ATI Radeon HD7770 video card.
> glxgears runs at poor 27 fps and videos are stuttering (playback with
> mplayer and different -vo options).

We don't do acceleration on southern islands or newer Radeon
parts because it depends on LLVM, glamor and drm backed EGL.
This also requires the gbm part of Mesa which until very
recently has only supported Linux and udev/systemd.

Yes, even basic 2d acceleration requires this mess because
xf86-video-ati only has OpenGL backed glamor acceleration
for these parts, they didn't write any normal X style acceleration.

In the default configuration, my cpu is running at 70-80 degrees C as reported by:

$ sysctl hw.sensors

I was able to cool it down about 20 degrees C with this (as root):

# sysctl hw.setperf=0

I'm sure there's a way to get that parameter set automatically on boot, but I leave that to you (or for me another day).

So now I'm getting CPU temps of 50 to 65 degrees C, which is 122 to 149 degrees F. Not horrible, but not anywhere near the 95 to 120 degrees F that I get in Linux.

I did a few other OpenBSD 5.6 tests. I installed the Firefox browser and then the Xfce desktop environment.

Both worked well. Video playback from YouTube stuttered quite a bit. Audio was low, even when boosted via the Xfce volume control.

Then I installed GNOME, which consisted of adding the metapackage and making a couple of configuration changes.

That went well. I had a working GNOME 3 desktop in OpenBSD 5.6. I must say, it is probably more responsive than GNOME 3 in Fedora. It's pretty much like it is in Debian, except for the CPU heat and the fan blowing.

So the combination of excessive heat and fan noise along with poor video performance means I won't be doing much with OpenBSD on this particular laptop.

But it's always instructive to check in on OpenBSD with various hunks of hardware to see how they work together. OpenBSD has always been a project to watch, and I can only hope that hardware compatibility improves as development continues.