On Tuesday 10 April 2007 23:17, Ramon Diaz-Uriarte wrote: > Of course, you are right there. I think that might still be the case. > At the time we made our decision, and decided to go for MPI, MPI 2 was > already out, and MPI seemed "more like the current/future standard" > than PVM.
That's always been the case. In fact MPI is a standard, where as PVM always was an implementation defining a so-called standard. > So using papply with Rmpi requires sharper programmers than using > snow? Hey, it is good to know I am that smarter. I'll wear that as a > badge :-). You are! I've never been patient enough to use plain Rmpi or rpvm except a few times, but for me, the advantage of snow is that you get all the backends, not just MPI. In fact, I've heard mention that some folks are sticking together a NWS backend as well. > Anyway, papply (with Rmpi) is not, in my experience, any harder than > snow (with either rpvm or Rmpi). In fact, I find papply a lot simpler > than snow (clusterApply and clusterApplyLB). For one thing, debugging > is very simple, since papply becomes lapply if no lam universe is > booted. In fact it might be easier, since we never put together decent aggregation routines. (smarter doesn't mean works harder, just more intelligently :-). > I see, though, that I might want to check PVM just for the sake of the > fault tolerance in snowFT. Fault tolerance is one of those very ill-defined words. Specifically: #1 - mapping pRNG streams to work units, not just CPUs or dispatch order (both of which can differ), for reproducibility #2 - handling "failure to complete" on worker nodes gracefully. However, you'd need checkpointing or probably a miracle to handle failure on the master... best, -tony [EMAIL PROTECTED] Muttenz, Switzerland. "Commit early,commit often, and commit in a repository from which we can easily roll-back your mistakes" (AJR, 4Jan05).
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