Re: [Mesa3d-dev] New tdfx driver, locking, small device driver changes

[Keith W. <ke...@va...>]

Brian Paul wrote:
> 
> Keith Whitwell wrote:
> >
> > OK, so in examining the newest tdfx driver, I got to wondering about the calls
> > to LOCK_HARDWARE inside the triangle functions.  In particular, after noticing
> > the slowdown after Brian added cliprect handling to those calls, I wondered
> > what would happen if I moved locking out of the triangle function.
> >
> > The answer was suprising:
> >
> >                         old             lock in         cliprect        lock outside
> >                         trunk           trifunc         in trifunc      trifunc
> >
> >         gears           448             560             550             650     fps
> >         isosurf         56              60              60              85      fps
> >         trispd-50       520k            572k            567k            921k    tris/sec
> >
> > on a celeron 400 with a v3-3000.  We are getting close to a 50% overall
> > speedup on this branch (and better for certain apps)...
> >
> > So...  What's the catch?
> >
> > Basically, to lock outside the trifuncs, I need somewhere to lock.  The
> > obvious place is in the RenderStart/RenderFinish driver callbacks.  The only
> > trouble with this is the span fallbacks: we lock in these on a per-spanline
> > basis.  We can remove locking from the span callbacks, and be fine on triangle
> > rendering.  However, the span fallbacks are also called from DrawPixels, etc.
> >
> > DrawPixels, etc. don't currently call RenderStart/RenderFinish, so where
> > should the locking occur there?
> >
> > To my mind, the obvious thing to do is:
> >
> >         - Add RenderStart/RenderFinish calls around all possible calls to the
> > span/pixel functions
> >         - Do locking in RenderStart/RenderFinish in the tdfx driver
> >         - Remove locking from triangle and spanline functions in the tdfx driver
> 
> That's what I would do.
> 
> I can add the RenderStart/Finish calls to Mesa (if you haven't already).
> glClear also uses the span functions, BTW.

That would be helpful - I'm looking at other consequences of this (relating to
transition between single and multiple cliprects) at the moment.  

Keith