MPI: Gather Communication

Listed below are MPI_Gather communication times for a variety of message sizes and processor partitions. The total communication time is listed in terms of CPU clock cycles, and the bandwidth is listed in megabytes per second.

2 processors

  CPU cycles per word for 256 word messages is 62.753906 (4.30 Mbytes/sec)
  CPU cycles per word for 512 word messages is 34.145508 (7.91 Mbytes/sec)
  CPU cycles per word for 1024 word messages is 19.116211 (14.12 Mbytes/sec)
  CPU cycles per word for 2048 word messages is 12.326660 (21.90 Mbytes/sec)
  CPU cycles per word for 4096 word messages is 10.711670 (25.21 Mbytes/sec)
  CPU cycles per word for 8192 word messages is 9.401550 (28.72 Mbytes/sec)
  CPU cycles per word for 16384 word messages is 8.664093 (31.16 Mbytes/sec)
  CPU cycles per word for 32768 word messages is 7.524948 (35.88 Mbytes/sec)
  CPU cycles per word for 65536 word messages is 6.729813 (40.12 Mbytes/sec)
  CPU cycles per word for 131072 word messages is 6.443481 (41.90 Mbytes/sec)
  CPU cycles per word for 262144 word messages is 12.429914 (21.72 Mbytes/sec)
  CPU cycles per word for 524288 word messages is 15.322065 (17.62 Mbytes/sec)
  CPU cycles per word for 1048576 word messages is 17.131784 (15.76 Mbytes/sec)
  CPU cycles per word for 2097152 word messages is 18.737730 (14.41 Mbytes/sec)
  CPU cycles per word for 4194304 word messages is 15.343791 (17.60 Mbytes/sec)

4 processors

  CPU cycles per word for 256 word messages is 98.613281 (2.74 Mbytes/sec)
  CPU cycles per word for 512 word messages is 53.789062 (5.02 Mbytes/sec)
  CPU cycles per word for 1024 word messages is 32.827148 (8.22 Mbytes/sec)
  CPU cycles per word for 2048 word messages is 17.731934 (15.23 Mbytes/sec)
  CPU cycles per word for 4096 word messages is 12.837524 (21.03 Mbytes/sec)
  CPU cycles per word for 8192 word messages is 13.125916 (20.57 Mbytes/sec)
  CPU cycles per word for 16384 word messages is 12.075348 (22.36 Mbytes/sec)
  CPU cycles per word for 32768 word messages is 9.897995 (27.28 Mbytes/sec)
  CPU cycles per word for 65536 word messages is 8.371582 (32.25 Mbytes/sec)
  CPU cycles per word for 131072 word messages is 7.542458 (35.80 Mbytes/sec)
  CPU cycles per word for 262144 word messages is 7.112703 (37.96 Mbytes/sec)
  CPU cycles per word for 524288 word messages is 6.919971 (39.02 Mbytes/sec)
  CPU cycles per word for 1048576 word messages is 6.844332 (39.45 Mbytes/sec)
  CPU cycles per word for 2097152 word messages is 6.827306 (39.55 Mbytes/sec)
  CPU cycles per word for 4194304 word messages is 6.792753 (39.75 Mbytes/sec)

8 processors

  CPU cycles per word for 256 word messages is 115.751953 (2.33 Mbytes/sec)
  CPU cycles per word for 512 word messages is 73.828125 (3.66 Mbytes/sec)
  CPU cycles per word for 1024 word messages is 37.639160 (7.17 Mbytes/sec)
  CPU cycles per word for 2048 word messages is 28.509521 (9.47 Mbytes/sec)
  CPU cycles per word for 4096 word messages is 16.067505 (16.80 Mbytes/sec)
  CPU cycles per word for 8192 word messages is 14.600830 (18.49 Mbytes/sec)
  CPU cycles per word for 16384 word messages is 14.386597 (18.77 Mbytes/sec)
  CPU cycles per word for 32768 word messages is 13.214493 (20.43 Mbytes/sec)
  CPU cycles per word for 65536 word messages is 11.075249 (24.38 Mbytes/sec)
  CPU cycles per word for 131072 word messages is 9.101315 (29.67 Mbytes/sec)
  CPU cycles per word for 262144 word messages is 8.181038 (33.00 Mbytes/sec)
  CPU cycles per word for 524288 word messages is 7.730298 (34.93 Mbytes/sec)
  CPU cycles per word for 1048576 word messages is 7.537308 (35.82 Mbytes/sec)
  CPU cycles per word for 2097152 word messages is 7.423464 (36.37 Mbytes/sec)
  CPU cycles per word for 4194304 word messages is 7.363259 (36.67 Mbytes/sec)