RE: [Algorithms] lights/shadows rendering architecture

[Tom F. <tom...@ee...>]

True, but it is a place where the GPU hardware is not working as hard as =
it
could, so if you're limited by GPU performance, it's going to hurt your
frames-per-second.

The other thing to consider is that some hardware can't do this stall
itself, it needs CPU assistance to help it. Which means it IS a CPU-GPU =
sync
point! Fortunately, that sort of hardware seems to be less common these
days.

TomF.

> -----Original Message-----
> From: gda...@li...=20
> [mailto:gda...@li...] On=20
> Behalf Of Jon Watte
> Sent: 23 September 2005 13:23
> To: gda...@li...
> Subject: Re: [Algorithms] lights/shadows rendering architecture
>=20
>=20
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> > There is only 1 GPU, but they have very long pipelines, and=20
> they also do a
> > lot of things in parallel. So the front of the pipeline can=20
> be trying to use
> > the texture before the end of it has finished, which it=20
> can't do, so it has
> > to stall.
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> But this is a "fake" stall -- more like a pipeline bubble.=20
> The CPU still=20
> keeps feeding stuff into the queue, so there's no GPU/CPU=20
> synchronization stall. Meanwhile, the GPU still keeps working without=20
> going idle (although some specific functional unit might be=20
> idle for a=20
> little while -- hence, the "bubble").
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> I guess how bad that is depends entirely on your GPU and your scene...
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> Cheers,
>=20
> 			/ h+
>=20
>=20
> --=20
> -- The early bird gets the worm, but the second mouse gets the cheese.