ServerWorks chipset

Mark Hahn hahn at coffee.psychology.mcmaster.ca
Sun Oct 15 11:02:18 EDT 2000


> Alpha systems have even higher bandwith with the same (or older) memory
> technology, this is a EV67 running at 667MHz with PC100 SDRAM (The
> system bus on Tsunami based Alpha systems run on 83MHz).

this bus may be only 83 MHz, but it's 4x as wide!

> Function     Rate (MB/s)  Avg time   Min time  Max time
> Copy:       1067.5483      0.0304      0.0300      0.0320
> Scale:      1057.2926      0.0307      0.0303      0.0313
> Add:        1067.0038      0.0454      0.0450      0.0460
> Triad:      1036.0382      0.0466      0.0463      0.0471

the chipset is very cool: fully populated with 4 banks and 8 d-chips,
it has a peak-theoretical bandwidth of 5.3 GB/s.  I suspect that 
this result (and the usual 1.2 GB/s one) are from not fully maxed
configurations, so their "Stream efficiency" is 1.1/2.6, rougly the 
same as to ia32 efficiency (550/1060)

unfortunately, very wide memory interfaces seem to be untenable in 
the commodity market.  and after all, Beowulf is about commodity...
(where 64b 133 MHz DDR sdram, "PC2100", seems to be the next step)

regards, mark hahn.


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