On Mon, 2008-03-10 at 19:53 +0000, James Stone wrote:
this is not how video display works. they are a lot like audio
interfaces actually. periodically, they interrupt the host CPU to say
"i'm about to start redrawing the screen from the framebuffer you last
told me about". that's about it really. they never redraw the screen at
any other time.
when your GUI toolkit decides to redraw a widget, it doesn't interact
with the h/w. all that happens is that eventually the new image of the
screen gets into the framebuffer, and on the next "VSYNC" cycle, the
video card will push it out to the actual display.
what is an issue is that the drivers and/or h/w associated with the
video card sometimes do not play fair with the PCI bus - they claim
owernship over it for too long while doing a redraw, and this *does*
lead to xruns at low latencies.
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