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--- unite_python_mpi_4_py [2026/04/10 13:35] – old revision restored (2026/04/10 13:00) nshegunov
+++ unite_python_mpi_4_py [2026/04/10 13:49] (current) – nshegunov
@@ Line 1: / Line 1: @@
-== MPI4py Ping-Pong Example for Cluster ==
+====== MPI4py Ping-Pong Example for Cluster ======
-MPI4py ping-pong demonstrates point-to-point communication between rank 0 (master) and rank 1 (worker). Rank 0 sends increasingly larger messages to rank 1, which echoes them back; timing measures bandwidth.
+This example shows a NumPy-based ping-pong benchmark using the ''mpi4py'' library on a cluster. Two MPI ranks exchange a NumPy array for several message sizes and measure round-trip time, one-way latency, and effective bandwidth.
+=====  Instructions =====
+To run this example, create the Python script and Slurm batch script provided below.
+The Python script uses the mpi4py library to measure MPI communication performance with the classic ping-pong benchmark. The Slurm script loads the required modules and submits the job across 2 nodes.
+Optional interactive testing:
+<code bash>
+srun --partition=short --ntasks=2 --gres=gpu:1 --time=02:00:00 --pty bash
+</code>
+Use this command to request an interactive session on a single node for experimentation.
 ===  Python Script (pingpong_mpi4py.py) ====
@@ Line 80: / Line 93: @@
 mpirun -np $SLURM_NTASKS python3 ./pingpong_mpi4py.py
 </code>
+===== Run =====
+<code bash>
+sbatch slurm_pingpong.job
+</code>
+===== Example output =====
+<code bash>
+Loading unite/python/3.14/mpi4py
+  Loading requirement: unite/python/3.14/python-3.14.0 unite/mpi/4.1
+size=       1 bytes | RTT=     10.08 us | latency=      5.04 us | bandwidth=      0.20 MB/s
+size=       8 bytes | RTT=      3.80 us | latency=      1.90 us | bandwidth=      4.21 MB/s
+size=      64 bytes | RTT=      4.49 us | latency=      2.24 us | bandwidth=     28.54 MB/s
+size=     512 bytes | RTT=     27.33 us | latency=     13.66 us | bandwidth=     37.47 MB/s
+size=    1024 bytes | RTT=      6.46 us | latency=      3.23 us | bandwidth=    317.16 MB/s
+size=    4096 bytes | RTT=      8.90 us | latency=      4.45 us | bandwidth=    920.86 MB/s
+size=   16384 bytes | RTT=     15.53 us | latency=      7.77 us | bandwidth=   2109.61 MB/s
+size=   65536 bytes | RTT=     29.86 us | latency=     14.93 us | bandwidth=   4390.07 MB/s
+size=  262144 bytes | RTT=     72.79 us | latency=     36.40 us | bandwidth=   7202.47 MB/s
+Ping-pong benchmark completed.
+</code>