Intel framebuffer compression & tiling update

[Matthias Hopf]

On Aug 16, 07 12:15:25 -0700, Jesse Barnes wrote:
> Framebuffer compression is an Intel feature that uses run length 
> encoding (RLE) to compress the front buffer to a separate compressed 
> buffer from which actual scanout occurs.  When enabled, if your desktop 
> is amenable to RLE, it can save as much as 0.7W in configurations I've 
> tested, due to reduced memory bandwidth consumption during scanout 
> (i.e. reading a compressed scanout buffer uses less bw than reading the 
> full, uncompressed one).  It shouldn't measurably affect performance 
> adversely, since we've configured it to re-compress the front buffer 
> only every 1000 vblank events, nor should it increase power consumption 
> in any measurable way, even in pathological configurations.

Just being curious: how does this work with partial updates? Is the
compression line-based, so do you have a starting point per line and
only have to recompress the lines where something changed? Otherwise,
how would you deal with small changes like animated gifs in a webpage?

Thanks

Matthias

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