opteron VS Itanium 2

andreas boklund andreas.boklund at htu.se
Thu Oct 30 01:57:35 EST 2003

Just a note,

> For bandwidth/memory intensive codes, I think the Opteron is a clear
> winner in a dual processor configuration because of its dual channel
> to memory design.  Stream triad bandwidth during SMP operation is
> ~50% more than a one processor test.  Both the dual Pentium 4 and Itanium 
> 2 share their memory bus and split (with some loss) the bandwidth in 
> dual mode. 

This is true as long as you are using an applicaiton where one process has its own
memory area. If you would have 2 processes and shared memory the Opt, would
behave like a small NUMA machine and a process will get a penalty for accessing
another process (processors) memory segment.

To quote D. Barron, "If it seems to be to good to be true, it probably is!", i have never
yet seen true linear scalability, and with Ahmdahl out there i doubt that i ever will.


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