Hi Niyaz, The triplet meanings are (start node id, number of nodes, processes per node), and processes are assigned round-robin fashion. So "(0, 2, 1)" with 2 processes on 2 nodes expands into "0, 1" - first process on node 0 and 2nd process on node 1. Hope that helps. -- Hui ________________________________ From: Niyaz Murshed via discuss <[email protected]> Sent: Wednesday, August 7, 2024 12:18 PM To: [email protected] <[email protected]> Cc: Niyaz Murshed <[email protected]>; nd <[email protected]> Subject: [mpich-discuss] How to read --pmi-process-mapping Hello, I am launching 2 processes on 2 nodes. The processes get rank 0 and 1 --version 4. 3. 0a1 --iface-ip-env-name PMI_HOSTNAME --hostname 192. 168. 2. 100 --global-core-map 0,1,2 --pmi-id-map 0,0 --global-process-count 2 --auto-cleanup 1 --pmi-kvsname ZjQcmQRYFpfptBannerStart This Message Is From an External Sender This message came from outside your organization. ZjQcmQRYFpfptBannerEnd Hello, I am launching 2 processes on 2 nodes. The processes get rank 0 and 1 --version 4.3.0a1 --iface-ip-env-name PMI_HOSTNAME --hostname 192.168.2.100 --global-core-map 0,1,2 --pmi-id-map 0,0 --global-process-count 2 --auto-cleanup 1 --pmi-kvsname kvs_31321_0_150440369_ampere-altra-2-1 --pmi-process-mapping (vector,(0,2,1)) I see once rankmap is generated, its converted to a string “(vector,(0,2,1))”. How do we read this as? Regards, Niyaz