Re: Plan 9 grids with AMD64 CPUs

>>The Plan 9 OS was written in real mode, and the its applications are 
>>all 16 bit. For grid use, it seems that Plan 9 would only be a good
>>choice for creating inexpensive low performance grids. 

it is in that unreal `real' mode only for a small
fraction of instructions when booting.
it runs in 32-bit protected mode, as is usual,
and indeed the compilers don't support the 16-bit mode.

(doing a compiler suite for the 64-bit architecture wouldn't be all that hard.)

>>provides. Granted, there aren't many applications that need
>>a great deal of computational power; yet. :-/

i'm curious about this: apart from the hype and artificial benchmarks,
for an arbitrarily chosen real computational program,
how much faster is it?

for things that do lots of work on genuinely
64-bit integer values, i can see it (otherwise you're just shifting more zero bits
round the machine).  for floating-point, given that the 387 instructions
were rather clumsy, if you can get that many more things into real
registers, i can also see it--i suppose.  even then, the later x86-based
architectures have shadow registers behind the scenes, managed
by hardware, which is why they are quite competitive with
RISC machines (fiendishly complex inside, but that turns out not to matter).
the data paths in the modern x86 devices are already at least 64 bits.

in short, apart from artificial benchmarks, what improvements
do people see on real applications and just as important,
what actually makes the difference?

another justification i've seen that does make sense is to use 64-bit addressing for
applications that need a huge directly-addressible memory (not that there
are too many of those applications, or that they couldn't be a bit cleverer).