Well I have no luck in finding a way to up the amount the system will allow GM to use. What is a recommended solution? Is this even a problem in most cases? Like am i encountering a corner case?
upping the limit was not what i'm suggesting as a fix, just pointing out that it is kind of low and even with a fully working ompi or mpich-gm. ompi should still work, even if the IOMMU limit is low.
Since you are running 1 thread per CPU (== 2 total), it is possible (likely) that the 1st thread is grabbing all the available registerable memory, leaving not even enough for the second thread to even start. I recommend you try the "mpool_rdma_rcache_size_limit" that Gleb mentions - the equivalent setting is used in MPICH-GM in similar situations. Set this to about 180 MB and run with that.
Gleb - I assume that when registration needs exceed "mpool_rdma_rcache_size_limit", that previously registered memory is unregistered much as virtual memory is swapped out?
regards, -reese
