[Beowulf] cluster softwares supporting parallel CFD computing

[Stuart Midgley]

>
> It does apply, however, many parallel algorithms used today are
> naturally blocking. Why?  Well, complicating your algorithm to overlap
> communication and computation rarely gives a benefit in practice. So
> anyone who's tried has likely become discouraged, and most people
> haven't even tried.
>
> -- greg


You comment about overlapping computation and communication is  
interesting.  As the number of cores per address space goes up, the  
chance that overlapping computation with communication actually gives  
you anything also decreases... memory copies require CPU intervention  
(unless you offload it to your NIC which then means you suffer the  
normal latencies/message rates etc there).

Sure, you can offload the copy to the NIC on some interconnects (eg.  
Quadrics) but I personally found that the increased latency and  
decreased bandwidth of the copy affected performance more than not  
overlapping.


--
Dr Stuart Midgley
sdm900 at gmail.com