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Subject: Re: [OMPI users] specifying hosts in mpi_spawn()
From: Ralph H Castain (rhc_at_[hidden])
Date: 2008-06-02 08:30:47

Appreciate the clarification. Unfortunately, the answer is ³no² for any of
our current releases. We only use the ³host² info argument to tell us which
nodes to use ­ the info has no bearing on the eventual mapping of ranks to
nodes. Repeated entries are simply ignored.

I was mainly asking for the version to check if you were working with our
svn trunk. The upcoming 1.3 release does support mapping such as you
describe. However, it currently only supports it for entries in a hostfile,
not as specified via ­host or in the host info argument.

Historically, we have maintained a direct correspondence between hostfile
and ­host operations ­ i.e., whatever you can do with a hostfile could also
be done via ­host. I¹ll have to discuss with the developers whether or not
to extend this to sequential mapping of ranks.

The short answer, therefore, is that we don¹t support what you are
requesting at this time, and may not support it in 1.3 (though you could get
around that perhaps by putting the ordering in a file).


On 5/30/08 11:32 AM, "Bruno Coutinho" <coutinho_at_[hidden]> wrote:

> I'm using open mpi 1.2.6 from the open mpi site, but I can switch to another
> version if necessary.
> 2008/5/30 Ralph H Castain <rhc_at_[hidden]>:
>> I'm afraid I cannot answer that question without first knowing what version
>> of Open MPI you are using. Could you provide that info?
>> Thanks
>> Ralph
>> On 5/29/08 6:41 PM, "Bruno Coutinho" <coutinho_at_[hidden]> wrote:
>>> > How mpi handles the host string passed in the info argument to
>>> > mpi_comm_spawn() ?
>>> >
>>> > if I set host to:
>>> > "host1,host2,host3,host2,host2,host1"
>>> >
>>> > then ranks 0 and 5 will run in host1, ranks 1,3,4 in host 2 and rank 3
>>> > in host3?
>>> > _______________________________________________
>>> > users mailing list
>>> > users_at_[hidden]
>>> >
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]