[PATCH 0/4] fb support for 8bpp bitmaps

Keith Packard keithp at keithp.com
Wed Jan 15 09:42:53 PST 2014

Eric Anholt <eric at anholt.net> writes:

> One of keithp's assumptions has been that you have
> reasonable-performance access to the texture memory for doing fallbacks.

It's actually a bit more subtle than that; what I want is to ensure that
when we switch to Glamor, we don't have any performance cliffs on
existing systems. The easiest way to ensure that is to make sure we can
fall back to the existing code without any performance penalty.

For systems which currently depend for performance on using the CPU for
some rendering operations, that means continuing to use those same paths
until we create replacement code that offers comparable performance.

Ideally, we'll eventually write code which makes all core operations
faster with the GPU than with the CPU.

> I'd like to see glamor do better at rendering without fallbacks, and I
> think ajax is also interested in pushing on that front.  It's certainly
> not there yet, though, so you need fallbacks and they need to be less
> awful if we want glamor to compare to native acceleration within this
> year.

Ideally, fallback performance under Glamor will match fallback
performance under UXA. Then, we can replace fallbacks one at a time with
even faster code and keep everyone happy with the switch.

keith.packard at intel.com
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