Tearing problem at bigger overlay sizes

[Xavier Bestel]

On Tue, 2009-01-13 at 18:55 +0100, Matthias Hopf wrote:
> On Jan 13, 09 18:39:10 +0100, Xavier Bestel wrote:
> > > Because the chip might reorder memory writes, and decide for later
> > > blocks to be pushed out first (or even pushed out to memory w/o changing
> > > the cache). That way you *could* see multiple tearings.
> > 
> > I thought a cache flush acted like a barrier, i.e. even if reordered
> > between them all writes before the flush should go.
> 
> Yes, but the beam could already in the middle of the screen if you flush
> only at the end of all blocks.

That would mean the engine isn't way faster than the beam, which I
thought was doubtful but after seeing the fillrate¹ of an r300 seems
plausible: around 1 Gtex/s means an HD screen (1920*1080 = 2 Gpix) would
take 2s to draw ... 
I must have missed something, it looks way too slow.

	Xav

1. http://en.wikipedia.org/wiki/Comparison_of_ATI_Graphics_Processing_Units#Radeon_R300_.289xxx.2C_X10xx.29_series