Re: Some perspective from the cheap seats...

> Sender: [email protected]
> From: Allen Akin <[email protected]>
> Date: Tue, 25 Mar 2003 22:53:44 -0800
> To: [email protected]
> Subject: Re: [forum] Some perspective from the cheap seats...
> -----
> On Tue, Mar 25, 2003 at 07:55:30PM -0800, [email protected] wrote:
> | I'll bet you a dinner it is at least two generations before we have both
> | FPU's and any significant 3d rendering assist in these devices.
> |
> | Understand, this is a bet I'd be very happy to lose :-).
>
> I'll take a bet, if you'll accept a modification. :-)

What modification?  Sounds like you don't like my FPU constraint.
I made it with eyes wide open, and for a good reason: bitter experience.

>
> Going by what I heard at the last ARB meeting, we're likely to have 3D
> assist before we have FPUs in the host processor.

Wouldn't surprise me in the least.  Intel, at least, didn't "get it" (see
below) when I last talked to them about FP; maybe one of the other embedded
chip vendors will.  Even single precision FP (which was planned originally
for what became XScale when it was still a Digital chip), would be a great help.

Even then, the low end devices will continue to use cheaper chips
for a while without.  Remember, battery consumption is *really* important;
you don't want powered up transistors you are not using, and you
really don't want to flap them, and god forbid you flap them off
chip.  On StrongARM, I can execute something
of order 100 instructions for the same power as accessing main memory even
once.  You start coding for joules, rather than cycles.

> In the near term
> generating FP data is likely to be less important than rendering it.
> Particularly for multiplayer and wireless.
>
Depends which market: our observation/experience about open source software on
handhelds is that lack of FP is one of the largest barriers to (usable)
porting of applications, particularly for multimedia apps.

This is compounded by the lack of (portable) good open source signal processing
library; many of the ones available are closed source and often only
available on a single architecture, and open source developers won't
touch them as a result of both of these factors.  Basically, the FPU's
in x86's became good enough about 4-6 years ago that most open source
developers stopped developing integer versions and just used the FPU).
I dunno the current state of integer implementations in freely available
OpenGL implementations; maybe one of the DRI folks would know and care
to enlighten this discussion; other wise, it is just hand waving on
the rendering side.

So in practice, the lack of FP hurts more than one might naively think,
at least in the market which we are mostly discussing here, and not
just for doing 3D graphics.
                               - Jim


--
Jim Gettys
Cambridge Research Laboratory
HP Labs, Hewlett-Packard Company
[email protected]