On my machine I need to use dynamic rules to enforce the bruck or pairwise algorithm for alltoall, since unfortunately the default basic linear algorithm performs quite poorly on my Infiniband network. Few months ago I noticed that in case of VASP, however, the use of dynamic rules via --mca coll_tuned_use_dynamic_rules 1 -mca coll_tuned_dynamic_rules_filename dyn_rules has no effect at all. Later it was identified that there was a bug causing the dynamic rules to apply only to the MPI_COMM_WORLD but not to other communicators. As far as I understand, the bug was fixed in openmpi-1.3.4. I tried now the openmpi-1.4 version and expected that tuning of alltoall via dynamic rules would work, but there is still no effect at all. Even worse, now it is not even possible to use static rules (which worked previously) such as -mca coll_tuned_alltoall_algorithm 3, because the code would crash (as discussed in the list recently). When running with --mca coll_base_verbose 1000, I get messages like
[compute-0-0.local:08011] coll:sm:comm_query (0/MPI_COMM_WORLD): intercomm, comm is too small, or not all peers local; disqualifying myself [compute-0-0.local:08011] coll:base:comm_select: component not available: sm [compute-0-0.local:08011] coll:base:comm_select: component available: sync, priority: 50 [compute-0-3.local:26116] coll:base:comm_select: component available: self, priority: 75 [compute-0-3.local:26116] coll:sm:comm_query (1/MPI_COMM_SELF): intercomm, comm is too small, or not all peers local; disqualifying myself [compute-0-3.local:26116] coll:base:comm_select: component not available: sm [compute-0-3.local:26116] coll:base:comm_select: component available: sync, priority: 50 [compute-0-3.local:26116] coll:base:comm_select: component not available: tuned [compute-0-0.local:08011] coll:base:comm_select: component available: tuned, priority: 30 Is there now a way to use other alltoall algorithms instead of the basic linear algorithm in openmpi-1.4.x ? Thanks in advance for any suggestion. Best regards Roman Martonak
