Re: 3D OpenGL applications eat CPU ressources

["Émeric Maschino" <emeric.maschino@gmail.com>]

2010/2/4 Jerome Glisse <glisse@freedesktop.org>:
> IIRC old radeon drm doesn't have any thing to dump GPU command stream.
> Look at http://www.x.org/docs/AMD/R5xx_Acceleration_v1.4.pdf to see
> what radeon GPU stream command looks like (packet pm4 stuff). Note that
> dump GPU command stream can quickly eat Gigs of data and finding what
> is causing the lockup is then very cumberstone especialy as in your
> case it sounds like it's a timing issue. You might want to force your
> card into pci mode to see if it's agp related.

Yep, setting Option "BusType" "PCI" in /etc/X11/xorg.conf prevents
from GPU lockup.

A a side note, strace glxinfo and strace glxgears still give me read()
errors on /tmp/.X11-unix/X0, so they're probably not related to GPU
lockup.

Anyway, I don't know whether this is due to PCI mode or not, but
OpenGL performances, although there's no more GPU lockup, are poor.
And serious OpenGL applications, as simulated by the SPECviewperf test
suite, have very irregular frame rates. If I'm not mistaken, the
BusType option is specific to the radeon driver (or maybe other
drivers too)? I mean, it's not a X.org wide configuration option,
isn't it? This would thus narrow my investigation path to the AGP code
of the radeon driver, right?

Émeric

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