Complete OSU Micro-Benchmarks keyboard shortcuts and commands reference — 12 shortcuts across 3 categories. Quick reference cheat sheet for Windows & Mac.
The OSU Micro-Benchmarks measure what an MPI library and its network actually deliver — latency, bandwidth, collective times — and they are the first thing to run on a new cluster before any application benchmark. The table lists the binaries; the notes explain which ones answer which question and how to run them on GPUs.
| Shortcut | Action | Description |
|---|---|---|
| osu_latency | Latency test | Measure round-trip latency for a single point-to-point message between two ranks. |
| osu_bw | Bandwidth test | Measure unidirectional bandwidth between two ranks. |
| osu_bibw | Bidirectional bandwidth | Measure bidirectional bandwidth with both ranks sending simultaneously. |
| osu_multi_lat | Multi-pair latency | Measure latency across multiple simultaneous rank pairs. |
| osu_mbw_mr | Multi bandwidth/message rate | Measure aggregate bandwidth and message rate across multiple pairs. |
| Shortcut | Action | Description |
|---|---|---|
| osu_allreduce | Allreduce latency | Measure MPI_Allreduce collective latency across all ranks. |
| osu_allgather | Allgather latency | Measure MPI_Allgather collective latency. |
| osu_alltoall | Alltoall latency | Measure MPI_Alltoall collective latency. |
| osu_bcast | Broadcast latency | Measure MPI_Bcast collective latency from a root rank. |
| osu_reduce | Reduce latency | Measure MPI_Reduce collective latency to a root rank. |
| Shortcut | Action | Description |
|---|---|---|
| mpirun -np 2 osu_bw d d | GPU-to-GPU test | Run the bandwidth test with buffers on the accelerator device ('D') instead of host memory ('H'). |
| osu_latency -m 2:128 | Set message range | Limit the test to message sizes between 2 and 128 bytes. |
The most essential OSU Micro-Benchmarks shortcuts are: osu_latency (Latency test), osu_bw (Bandwidth test), osu_bibw (Bidirectional bandwidth).
These are command-line commands — type them in your terminal or console. Combine them with shell history search (Ctrl + R) and aliases to work even faster.
The OSU Micro-Benchmarks shortcut for latency test is osu_latency. Measure round-trip latency for a single point-to-point message between two ranks.
OSU Micro-Benchmarks includes 5 Point-to-Point Tests shortcuts, including osu_latency (Latency test) and osu_bw (Bandwidth test). See the full list in the Point-to-Point Tests section above.
Yes — use My Stack to combine OSU Micro-Benchmarks shortcuts with any other platform on this site into one printable reference, which is useful if your daily workflow spans several tools.
osu_latency between two ranks on different nodes gives the round-trip half-time per message size; on a healthy InfiniBand fabric the small-message number is a few microseconds and anything higher points at a configuration problem. osu_bw and osu_bibw measure one-way and bidirectional bandwidth, which should approach the link rate for large messages. osu_multi_lat and osu_mbw_mr run several pairs at once for aggregate bandwidth and message rate, which is closer to what a real job does. osu_latency -m 2:128 restricts the message size range, useful for focusing on the small-message regime.
osu_allreduce is the one that predicts deep-learning performance, since gradient synchronisation is an allreduce; run it at the node count and message sizes your job uses. osu_allgather, osu_alltoall, osu_bcast and osu_reduce cover the other patterns, with alltoall the most sensitive to network topology. Compare results at 2, 4, 8 nodes to see how the fabric scales.
Built with CUDA support, the benchmarks take buffer-location arguments: mpirun -np 2 osu_bw d d measures device-to-device bandwidth (d for device memory, h for host, m for managed), which tests GPUDirect RDMA and is the number to check before trusting NCCL results. Launch through mpirun or srun with the same placement and binding flags as a real job, since binding changes the answer.
Open your assistant with this page preloaded as the source — great for follow-up questions like "which of these work in other apps?"