glx weirdness since xorg 7 modular

[Bilderbeek, Manuel]

Hi,

> When i start glxgears for example, the first second is fine, the gears
> rotate like they are supposed to.
> After 1 second though they stop, or at least it seems so, because if i
> wait another few seconds i realize that its still running.
> The fps in the console is still the same, the window just is updating
> very rarely.
> I get like 100 fps for example, but the gears only update 
> every 5 seconds.

If you ask me, everything is just working fine. The problem is that you
have stroboscopic interference between your screen updates and the
framerate that GLX achieves. It's like the wheel of a car that seems to
stand still on TV, while the car is clearly driving.

At moments when it does seem to work, there was probably a spike in the
CPU load, making the framerate drop a bit, which gets the thing just
"out of interference". 

> Meanwhile the cpu-load is at the max. but i dont know if that is how

That's normal, it tries to achieve the maximum possible framerate.

> it's supposed to be. It's hard to tell but i think in the first second
> when glxgears works fine the cpu-load is lower.

That's probably just because of the averaging.

> This is is not a important issue for me, but every now and then i
> cannot help but wonder why it worked fine in 6.8.2 but not anymore
> now.

You probably get a slightly higher (or possibly lower) framerate, which
suddenly triggers this interference effect. No worries, all seems just
fine!

Maybe this should be in some FAQ? (If it isn't already.)
--
Kind regards,

Manuel Bilderbeek

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