Re: 3D OpenGL applications eat CPU ressources

[Stephane Marchesin <stephane.marchesin@gmail.com>]

On Sat, Feb 6, 2010 at 11:47, Émeric Maschino <emeric.maschino@gmail.com> wrote:
> 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?
>

>From what I recall, all the ia64 AGP chipsets (well the zx1 and the
460) have to be run:
- without side band adressing
- without fast writes
- at 4x speed
otherwise they're unstable.

I think by default agpgart puts them at AGP 1x with fast writes...

Stephane

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