On Mon, Apr 07, 2008 at 07:54:38AM -0600, Ralph H Castain wrote: > > > > On 4/7/08 7:45 AM, "Gleb Natapov" <gl...@voltaire.com> wrote: > > > 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? > > The individual inbound messages are not currently compressed prior to > sending - too small to bother Make sense.
> > Also I think if rank=0 will compress each modex message during > > receive it can save some work during xcast. > > Seems to me like one compress of the entire message has to be a great deal > faster than N compressions of N small messages... The idea is that modex receive and compress will overlap. -- Gleb.