Comment (by Steven R. Brandt):

I recently attempted to run the gallery example on Deep Bayou. I set OMP_NUM_THREADS=4, and asked for 12 procs to run on the node (which has 48 cores according to lscpu). Cactus failed with this message cactus_sim: /nvme/sbrandt/Cactus/arrangements/Carpet/LoopControl/src/loopcontrol.cc:264: T <unnamed>::divexact(T, T) [with T = int]: Assertion i % j == 0' faile

It also said INFO (Carpet): This process runs on 24 cores. At Roland’s suggestion, I tried adding LoopControl::use_smt_threads = "no" to the par file and all was well. Maybe “no” is a more sensible default?

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                48
On-line CPU(s) list:   0-47
Thread(s) per core:    1
Core(s) --

Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/1326/running-loopcontrol-on-strange-number-of