[Xorg] Chromium vs GLX protocol

Alex Deucher alexdeucher at gmail.com
Thu Jul 29 08:17:16 PDT 2004

On Thu, 29 Jul 2004 08:20:33 -0600, Jens Owen <jens at tungstengraphics.com> wrote:
> Brian Paul wrote:
> > 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?
> >
> >
> > Sure...
> >
> >> 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.
> Brian,
> How about supporting key pieces of Chromium in the X.org release in
> addition to GLX?  Could integrating OpenGL API redirection, for example,
> make for a cleaner solution than what Chromium does with "app faker" today?

couldn't chromium be merged into xorg someday to provide multi-head
open GL in conjunction with dmx on the same box or different boxes? 
Say you have two 3d cards each could be brought up as independant X
servers with their own instances of the DRI.  Then chromium and DMX
could provide the middle layer so that multi-card hw Open GL would
just work for a xinerama desktop.


> --
>                                 /\
>           Jens Owen            /  \/\ _
>    jens at tungstengraphics.com  /    \ \ \   Steamboat Springs, Colorado
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