On Sunday 20 March 2005 12:48, Nicolai Haehnle wrote:
> 1. Run glxgears on a DRI-enabled system. Then run 'yes' in a terminal
> emulator. Watch the system go crazy.

Glxgears framerate drops by roughly half.  Balance changes from 90%/10% 
to 80%/20% user/system.  CPU usage splits roughly 50/50 between 
Glxgears and Konsole.  Why any of this happens is a mystery to me.

More copies of yes don't change the balance any further, except a 
grotesque bug in konsole/kde/qt emerges: the more konsole terminals 
running yes, the slower konsole echoes input characters.  With 18 
copies of yes running in 18 konsole windows, character echoing drops to 
less than 2 chars/second.  Other kde programs and Xterm are unaffected.  
I suspect this is a konsole-only bug.

> A similar effect can sometimes 
> be observed while moving and resizing OpenGL windows.

Glxgears nearly freezes when I drag its window, which is gross.  So is 
the idea of running an animation without any synchronization, for that 
matter.  I wonder how much of the problem is due to that.

This is on kernel 2.4.   Scheduling in 2.6 is radically different, but I 
haven't checked to see what happens.

> This suggests that access to the GPU needs a proper scheduler, just
> like access to the CPU is arbitrated using a proper scheduler.

I like proper schedulers :-)

Regards,

Daniel
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