Re: remapping myrinet while jobs are running

John C. Wright wrote:
> Hello list, I'm running gm-2.0.16_Linux on Linux version
> 2.4.20-28.7sm (RH7.3) on a 24  node cluster with dual athlon
> cpus on a Tyan board.
> I understand that gm now remaps from the initialization script
> and "negotiates" with the other nodes for the best network.  My
> question is  how can I set if a node needs to be rebooted while
> a program is running on  other nodes, that the remapping
> doesn't change the existing architecture?   I just what the
> node to reboot and "plug" itself back into the network map
> without recreating it, so the the existing job doesn't loose
> it's  connectivity and have to be restarted.
>
> I think this must be simple but I haven't been able to
> determine how to do  it from my reading of the documentation.
> Can anyone point me in the right direction?
>


You do not need to do anything special for this to work. The gm
"mapper" runs constantly and if you reboot a node or plug a new
one, it will be added to the configuration of everyone without
disturbing existing jobs (at worst there can be a very small
performance glitch at the time of the transition to the new
configuration because some packets might be lost. But that should
be completely transparent for the application. And the transition
will be very quick because the old network map will continue to be
used  while the "negotiation" to find the new one is ongoing. Only
once everybody has agreed on the new map, it is installed everywhere).


Loic