On Sun, 2002-04-21 at 21:34, Mark Vojkovich wrote:
> On 21 Apr 2002, Michel D�nzer wrote:
> 
> > On Sat, 2002-04-20 at 20:26, Mark Vojkovich wrote:
> > > On 20 Apr 2002, Michel D�nzer wrote:
> > > 
> > > > On Fri, 2002-04-12 at 02:23, Andrew P. Lentvorski wrote: 
> > > > > Okay, after tracking this, it turns out to be a pixmap cache bug.  At
> > > > > least, I can stop the problem from occurring by adding the "Option
> > > > > "XaaNoPixmapCache"" line to my XF86Config file.
> > > > 
> > > > That's coincidence, the same is true for "XaaNoScreenToScreenCopy".
> > > > 
> > > > The problem is that RADEONCPSetClippingRectangle() is called between
> > > > RADEONSetupForScreenToScreenCopy() and
> > > > RADEONSubsequentScreenToScreenCopy() and messes up the
> > > > DP_GUI_MASTER_CNTL register.
> > > > 
> > > > I don't see a proper solution to this problem so the attached patch just
> > > > disables hardware clipping for screen to screen copies. I wonder what
> > > > impact on performance this has, if any - Mark?
> > > 
> > >     Hard to say.  In some hardware implementations, hardware clipping
> > > is slower and it's fastest to clip in software.  It depends on how well
> > > the hardware optimizes away the unrendered pixels.
> > 
> > Can you recommend any benchmarks?
> 
>    There aren't any.  x11perf with the window half offscreen would
> test that though.  It's only used in "one-rect" situations.  If
> we don't have a complex cliplist (many rects) we know that we
> don't need to software clip any geometry, we can just set the
> hardware clip rect and send it all down without checking any of
> the primitives at all.   With smart hardware this is a win on a
> slow CPU.  It's less important as the CPU gets faster.  

Well, I think I may look into fixing the clipping for the CP case but
otherwise won't worry about performance until someone complains. Thanks
for the insights.


-- 
Earthling Michel D�nzer (MrCooper)/ Debian GNU/Linux (powerpc) developer
XFree86 and DRI project member   /  CS student, Free Software enthusiast
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