[Xorg] Chromium vs GLX protocol
brian.paul at tungstengraphics.com
Wed Jul 28 20:37:53 PDT 2004
Jon Smirl wrote:
> Slashdot is saying that SGI is going to port their clustered ATI
> graphics to Linux in the near future. The SGI page says this code is
> based on Chromium. I've read that the network protocol of Chromium is
> far better than the GLX protocol, especially in the area of state
> management. Does anyone have experience with both protocols and can
> comment on how they compare?
> If the Chromium protocol really is a lot better would it make sense to
> evaluate shifting our focus from GLX to the Chromium protocol? In the
> long run the coming shift to things like X on GL and Glitz may
> ultimately move a lot of network traffic from the X protocol to one of
> the GL ones. If Chromium is significantly better wouldn't it be wiser
> to change the X server GL protocol now rather than later?
The Chromium command packer packs GL commands more densely than GLX.
A one-byte opcode is used for most commands and operands are packed
tightly in memory. Opcodes are packed separate from the operands in a
unique way too.
Chromium also has a state tracking system which can eliminate
redundant commands from being packed/sent. It's pretty complicated
though and still a source of bugs.
I wouldn't say that Chromium's packer is a *lot* better than GLX. And
I wouldn't advocate switching to it. GLX interoperability is
important and making such a switch would upset that. I don't think
the effort to switch would be worth the trouble. Performance-wise, I
think the gains would be quite modest.
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