Scali, proprietors of several high performance computing software packages, recently cut a press release entitled “Scali demonstrates that the choice of MPI is three times more important than the selection of compilers.” Uhhhh…. What!?
Scali is touting the results of its latest version of Scali MPI Connect version 5.6.1 on the SPEC MPI2007 benchmark. The results reflect the 13 applications contained with the SPEC MPI2007 medium suite running on 32 nodes [128 cores]. Apparently, three of the applications came within +/- 2 percent of a similar system running HP-MPI . However, they are seeing performance results of 21 percent faster on Socorro and 336 percent faster on POP2 [both over HP-MPI]. Scali went on to run the same suite of benchmarks using different compilers. The results looked as if changing compilers only allowed for a 6 percent increase in performance.
Now, I can already hear all you performance gurus grinding your teeth. I, for one, have run quite a few different MPI variants in production over the years [open source and commercial]. I’ve actually sat and watched Scali’s MPI Connect outperform several open source varients on POP [...thanks Jim Tuccillo]. However, I vehemently disagree with the statement that MPI is everything. What happens when your code is only utilizing MPI for very simple and occasional synchronization tasks? I highly doubt that Scali’s `MPI_Barrier` is 18 percent more efficient than any other variant.
Just for the record, I’m not beating up on Scali. I truly believe MPI Connect is a good product for several applications [POP being one of them]. However, lets go ahead and say it together: “…Its application dependent.”
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