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Subject: Re: [OMPI devel] Affect of compression on modex and launch messages
From: Gleb Natapov (glebn_at_[hidden])
Date: 2008-04-07 09:45:12


On Mon, Apr 07, 2008 at 07:28:07AM -0600, Ralph H Castain wrote:
> > Also can you explain how
> > allgather is implemented in orte (sorry if you already explained this once
> > and I missed it).
>
> The default method is for each proc to send its modex data to its local
> daemon. The local daemon collects the messages until all of its local procs
> have contributed, then sends the collected data to the rank=0 application
> proc. One rank=0 has received a message from every daemon, it xcasts the
> collected result to all procs in its job.
>
Only collected result is compressed or messages from each proc to local
daemon and messages from local daemon to rank=0 are compressed too?
And, may be a stupid question, but I have to ask :) When rank=0 xcast
collected modex it compress it once or for each rank separately.
Also I think if rank=0 will compress each modex message during
receive it can save some work during xcast.

--
			Gleb.