[Beowulf] Cell

Ben Mayer bmayer at gmail.com
Wed Apr 27 12:07:02 EDT 2005


On 4/27/05, Vincent Diepeveen <diep at xs4all.nl> wrote:
> At 06:45 PM 4/26/2005 -0400, Mark Hahn wrote:
> >> Obviously clever governments, who currently have giants of supercomputers
> >> which costs several million, will conclude they can buy a few cheapo cell
> >> processor machines which do more work than the entire system currently.
> >
> >this is ridiculous.  the Cell is basically a GPU - slightly more general
> >than the current-gen GPUs from Nvidia and ATI, but not drastically different.
> 
> Cell is from my viewpoint a vector floating point processor which only
> disadvantage is executing branchy code.
> 
> Just like Cray machines were in the past vector processors.

Their current machine (X1E) is a vector machine. The problem on that
machine is that the code needs to vectorize. You can do it with the
compiler or libraries, but it HAS to vectorize to get that
performance. Cray's current machines depend on the compiler and highly
trained humans writing code (they have some libraries for specific
things like sequence alignment) to make things run faster then a
Pentium 4. Granted when they do run faster, it is a 32-64x speed up
*per CPU*.

The people writing code for the PS3 (Cell) are going to have some
experience writing parallel vector code because that is what the PS2
was. But I will be very surprised if they can consistently get more
then 10% of peak.


> A gpu doing effectively 256 gflop for just a few dollar would be nice.

GPUs are often time doing calcs at half precision.

> 
> See supercomputer reports europe.
> 
> So there is a BIG need for a CHEAP vector processor doing floating point
> there.

Is it processors that they need or bandwidth?

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