During the 1.7 series, we changed things at the request of system admins so that we don't oversubscribe allocations given to us by resource managers unless specifically told to do so.
On Fri, Aug 14, 2015 at 12:52 AM, Schlottke-Lakemper, Michael < m.schlottke-lakem...@aia.rwth-aachen.de> wrote: > Hi folks, > > It seems like oversubscription is disabled by default in OpenMPI 1.8.7, at > least when running on a PBS/torque-managed node. When I run a program in > parallel on a node with 8 cores, I am not able to use more than 8 ranks: > > > mic@aia272:~> mpirun --display-allocation -n 9 hostname > > > > ====================== ALLOCATED NODES ====================== > > aia272: slots=8 max_slots=0 slots_inuse=0 state=UP > > ================================================================= > > > -------------------------------------------------------------------------- > > There are not enough slots available in the system to satisfy the 9 slots > > that were requested by the application: > > hostname > > > > Either request fewer slots for your application, or make more slots > available > > for use. > > > -------------------------------------------------------------------------- > > > However, if I specifically enable oversubscription through the > rmaps_base_oversubscribe setting, it works again: > > > mic@aia272:~> mpirun --display-allocation --mca > rmaps_base_oversubscribe 1 -n 9 hostname > > > > ====================== ALLOCATED NODES ====================== > > aia272: slots=8 max_slots=0 slots_inuse=0 state=UP > > ================================================================= > > aia272 > > aia272 > > aia272 > > aia272 > > aia272 > > aia272 > > aia272 > > aia272 > > aia272 > > Now I am wondering, is this a bug or a feature? We recently upgraded from > 1.6.x to 1.8.7, and as far as I remember, in 1.6.x oversubscription was > enabled by default. > > Regards, > > Michael > > P.S.: In ompi_info, both rmaps_base_no_oversubscribe and > rmaps_base_oversubscribe are reported as “false”. Our > prefix/etc/openmpi-mca-params.conf file is empty. > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2015/08/27466.php
