Messages in this thread | | | Date | Mon, 27 Oct 2003 10:43:09 -0500 | From | Jeff Garzik <> | Subject | Re: [Dri-devel] Re: [Linux-fbdev-devel] DRM and pci_driver conversion |
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On Mon, Oct 27, 2003 at 04:37:30PM +0200, Ingo Oeser wrote: > On Saturday 25 October 2003 21:17, Jeff Garzik wrote: > > Graphics processors are growing more general, too -- moving towards > > generic vector/data processing engines. I bet you'll see an optimal > > model emerge where you have some sort of "JIT" for GPU microcode in > > userspace. Multiple apps pipeline X/GL/hardware commands into the JIT, > > which in turn pipelines data and microcode commands to the GPU kernel > > driver. > > These "JIT" is needed also for another reason: > > There are contraints for GPU commands and the pipelines need to > be modelled, like CPU piplines are modelled in a compiler. But > more like the pipelines of some early long instruction word > processors, where issuing to a used pipeline will cause random > behavior and crashes. So the JIT doesn't should also emit > synchronization points. > > With this JIT in place, there need to be just some hardware description > files (backends) and some API (GL, DirectX, X) description files > (frontends).
I agree 60% ;-) This JIT emits GPU-specific microcode, so it should lean towards being hardware-dependent. Speed and efficiency IMO demand that.
Looking at existing, open-source CPU JITs, there are certainly general pieces and CPU-specific pieces. But for GPUs, I think the best method is to start at the more-GPU-specific end of the spectrum, and _evolve_ towards a more general solution, as hardware needs dictate.
In other terms, let the hardware drive the JIT design and evolution, and don't over-design for a future that may never come. That was part of GGI's problem, IMO.
> Now we just need some funding for that and the datasheets. Then it's > doable.
Yep ;-)
> I see just one showstopper: Cheating in benchmarks isn't possible anymore. > > PS: That's basically the GGI approach taken further.
I followed GGI for a while. Trying to be all things to all people was their principle mistake. As Pat Morita said in Karate Kid, "Focus, Daniel-san!" Be specific before general.
Jeff
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