[R-sig-hpc] Rmpi on Mac OS X 10.5.8 dual core machine

[Benilton Carvalho]

Hi Ross,
thank you very much for the clarification.
With best wishes,
b

On Dec 11, 2009, at 10:01 PM, Ross Boylan wrote:

> On Wed, 2009-11-18 at 17:09 -0200, Benilton Carvalho wrote:
>> Hi,
>> 
>> I decided to experiment with Rmpi on my dual core machine (Mac OS X
>> 10.5.8).
>> 
>> So, I try the usual:
>> 
>> library(Rmpi)
>> mpi.spawn.Rslaves()
>> 
>> and let R "sit there"... I expected the R process to be idle, but for
>> my surprise it uses, at least, 70% of CPU.
>> 
>> Is this an expected behavior?
> I'd expect 100%, but that's based on a Linux cluster.
> OMPI does busy waiting, i.e., it runs in a tight loop checking for data.
> So it uses lots of CPU even when it's doing nothing.
> 
> The developers made this choice to increase the responsiveness on MPI,
> based partly on the assumed target use-case involving a cluster in which
> nodes were allocated entirely to the job running under MPI--i.e.,
> nothing else we need the CPU.
> 
> Ross
>> I'm currently assuming I'm missing
>> something obvious.
>> 
>> Also, on a Mac OS X system, is Rmpi supposed to work without LAM?
>> 
>> Hao Yu's page makes me think it is a requirement, but, on my system,
>> it found OpenMPI, so I didn't install LAM....
>> 
>> Comments,
>> 
>> b
>> 
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>