[Mesa-dev] r600g/mesa/gallium performance, whois to blame ?

[Keith Whitwell]

On Fri, 2010-11-12 at 20:32 -0800, Jerome Glisse wrote:

> 
> I think r600c is just a bit too naive and so it end up being very
> expensive to change any states with it. But i haven't took a closer
> look. I don't think we should look too much at relative cost of
> changing state. I think fglrx optimized the function call cost just
> enough so that it didn't impact performances, while nvidia did go nuts
> and over optimized function call overhead. Thus i think target should
> be more about making sure core mesa + gallium with noop pipe driver
> should be able to keep up at 500t draw call/sec when states change
> occur (of course this could vary depending on which states change) and
> not 173t call/sec.

I think the idea of installing a noop pipe driver & using that to
optimize everything else in the stack is a good one.

It's true that the per-statechange overhead hasn't really had a lot of
attention in the Mesa statetracker, and in particular there is a lot of
work done every draw call to re-assemble all of the vertex buffers and
vertex elements.

A lot of that could be short-circuited with a little effort.

Keith