energy costs

Richard Walsh rbw at ahpcrc.org
Wed Mar 12 11:48:58 EST 2003


On, Wed, 12 Mar 2003 10:19, Robert Brown:

>> > 200/5600 = .0357 or 3.57% (so 5% is a gift)
>> 
>> oh, I see.  to me, that's a strange definition of "peak",
>> since stream is, by intention, always bottlenecked on 
>> memory bandwidth, since its FSB is either 3.2 or 4.3 GB/s.
>> it'll deliver roughly 50% of that to stream.
>
>Stream also generally does not deliver worst case memory bandwidth --
>far from it.  A "streaming" pass through memory allows all sorts of
>prefetch optimizations to be done that partially parallelize the memory
>access times, as does e.g. SDRAM's basic architecture (which
>accomplishes similar parallelization on a smaller scale).

True. Stream gives the most vector-like view of non-vector ISA's like
IA-32 and such. Pre-fetch is "just another word for nothing we can
vector load." I am tossing dwarf vectors (SSE, SSE2, etc.). No pun-y
intended.

And, I give a catechistic node of approval to Robert's ...

covers-the-point-like-a-coat-of-paint-covers-a-room ...

;-) remarks.  

Rock-on,

rbw

_______________________________________________
Beowulf mailing list, Beowulf at beowulf.org
To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf



More information about the Beowulf mailing list