[MPICH] Idle processes at 100% load with ch3:ssm and nemesis, but not ch3:sock

[Nate Crawford]

Hi All,

  I am having a significant problem using shared memory for intra-node
communications with MPICH2-1.0.5p3 (and some earlier versions). Some of
our parallel programs are based on a master/slave arrangement where the
master coordinates the slaves, but does no real work. When using sockets
for intra-node message passing, things work as intended: the master is
nearly always idle, and all but one of the slaves are idle during the
sequential parts. With ch3:ssm or nemesis, all processes are always
using 100% CPU, even when they are only waiting for the signal to
proceed.

  I suspect that the waiting processes are not using the best method for
receiving messages, but do not know what to look for. Is this known
behavior? I compiled MPICH2 with gcc 4.1.2 and pgf90 6.2-2 on SuSE 10.2
(x86-64).

Thanks,
Nate

-- 
__________________________________
Dr. Nathan Crawford
Theoretische Chemie
Universität Karlsruhe