[Beowulf] MIT Genius Stuffs 100 Processors Into Single Chip

Vincent Diepeveen diep at xs4all.nl
Tue Jan 24 10:25:07 PST 2012


I remember the first announcement some years ago from Tilera.
Some persons shipped some emails to tilera asking for more details.
Some just asked - like me - others also offered money to buy a cpu.

They all got a 'no'.

But now that there are more details the chip sounds less impressive.
Let's analyze based upon the vague information on the homepage.

Lots of statements that a marketing department in India would write  
down as such
are there as well; reformulating existing slogans into more political  
slogans,
allowing you to deny later on that it performs very well. We know  
that trick just all
too well.

First of all homepage report it's 23 watts, yet doesn't say whether  
that's idle or under full load.
It just says 'active'. Active is a vague way of formulating. I assume  
that's a core that isn't idle yet
isn't under 100% load. So then it eats like a portion of the power.

So probably it's a watt or 50 under full load.
Then it says 64 cores in a grid @ 700Mhz.

700Mhz sounds as a possible Ghz frequency that you can get if you're  
a professional
(if i'd build something count at it that it'll run 300Mhz or so).
Doesn't seem like weird claim.
64 * 0.7 = 44.8Ghz measure
Yet at the same time it claims on homepage 443 billion operations per  
second.
What is an operation? Is that an internal iop?
It says it's 32 bits VLIW. So that would mean it's processing each  
cycle 10 integers.
Now we know from all other manufacturers they cheat factor 2, by  
double counting if just 1 instruction theirs is doing for example  
Fused Multiply Add.
So we can divide it by 2 probably and get to 220 gflop.
So then a vector would be 5 integers long, which seems like a weird  
measure.
Maybe they rounded it up a tad and in reality mean 4 integers, sounds  
most reasonable.
So then it's 64 cores in a grid executing vectors existing out of 4  
units of 32 bits. Sounds plausible.

If we compare that with some GPU's which are in our notebooks from a  
few years ago, then suddenly it's not so impressive.

Vincent

On Jan 24, 2012, at 5:24 PM, Eugen Leitl wrote:

>
> http://www.wired.com/wiredenterprise/2012/01/mit-genius-stu/



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