Re: P1788: Punish?
And you can also pose the question, how will the marketplace punish firms
who do NOT provide full HW support for P1788 - but rely instead on software?
What is going to drive firms to provide P1788 in HW - with all due respect I
don't see how P1788 is going to provide that driving force - yet.
Good question. Let me give it a try.
Hopefully, I won't write too many trivialities.
I agree that IA doesn't have an outstanding "killer app that drives
big sales". But let's try to turn this into a selling point ! :)
The thing is that I don't see that "one killer app" is rarely the
reasoning behind the integration of a feature in a common HW. It
could be the motivation when the target is a niche market with dedicated
hardware possibilities, but I don't think that is a concern here.
Let's look at the features now supported by e.g. x86 CPUs :
multi-core, SIMD (vector computations), AES (encryption),
profiling counters, debugging support, OS virtualization, RNGs...
Most of them, if not all, are not driven by one particular application,
but they are driven by general computing needs. The direction is
a balanced CPU. The question is : what will they do next with the
available space on the die ? More cores ? OK. But let's not forget
that it takes time to parallelize apps, and the software industry as
a whole is slow. More [sequential] functionality is also useful, and
the question is whether IA can be a candidate, and a competitive one.
IA could help making good use of those SIMD units for more apps at least.
To me, IA essentially competes with floating-point arithmetic
as a computing model for approximation of real functions, and
it is the way it should be sold.
FP is a terrible model, as its properties do not compose. I mean,
there is a nice 0.5 ulp error for a+b, but as soon as you do a+b+c
you cannot say anything interesting anymore without a headache.
What do we want with real numbers? Well, it's about quantifying
the approximation that you get for the evaluation of a function.
IA does just that. Sure, you can somehow emulate IA with FP
in various ways, e.g. by doing static error analysis,
which is complicated as hell. In short : it costs a lot in
terms of learning, research, and paying experts. The alternative is
for the HW to account for the rounding error. Is it time for this ?
The FP model is dominant in software also precisely because it has
so little support in HW : languages compete on speed, so they only
offer types which they can provide efficiently, and there is a
chicken and egg problem here if you are looking for wide adoption
of IA before deciding to support it in HW.
It's true that the priority was given to things like graphics and
games lately, but aren't we reaching the bottom of this now ?
( An interesting anecdote here : a colleague of mine won a
"best paper" price at a well known graphics conference, the prize
being the latest nVidia card. He did not need it so he tried
to sell it on eBay, thinking that gamers would jump on it,
being the high-end of those cards... But no gamer bought it,
since it was a complete overkill even for the most demanding games.
It was already 2 years ago. )
Now, Intel knows that certification has a price. I read that the
Pentium bug cost about 500 million dollars, and they worked hard
on proving their CPUs. Many software areas need certification as well.
They may use software-IA now, or maybe they don't but would switch
to it, especially if it was faster thanks to HW support.
It's a bit like HW-assisted encryption : if you don't have it,
you wonder whether you should enable it, so you take some risks,
but if you have it "by default, at basically 0 cost", then you
remove the question completely and you are safe.
At a high level, the selling point is "IA helps making software less
buggy", or "helps making efficient and robust software more easily".
Everybody knows that computers have bugs and compute approximately,
and tackling this issue is hopefully a selling point understandable
by everyone. Marketing guys can feel free to re-baptize IA to some
funny name, like AMD used "3DNow!". I'm sure they are good at that :)
Since no chip maker currently ships HW-IA, what can break the
status quo ? How did this happen for the first FP co-processors ?
And for the first SIMD units ?
As for "*full* support", I think it need not be full in HW. It can
also be done progressively. Like the SSE/SSE2/.../SSEn have introduced
more and more types and functions.
I guess that Intel has ways to evaluate the needs of the various
industries, except maybe that, with time, once the low hanging fruits
have been considered, it gets harder to choose the next one (?).
Quantifying the gains and costs is also something we can hardly do here.
I would really like to see a word from Intel or any similarly big
player on the subject (official or not).
My 0.02 Euros.
--
Sylvain