MPI: AlltoAll Communication

Listed below are MPI AlltoAll 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.

4 processors

  CPU cycles per word for 256 word messages is 183.779297 (1.47 Mbytes/sec)
  CPU cycles per word for 512 word messages is 117.729492 (2.29 Mbytes/sec)
  CPU cycles per word for 1024 word messages is 60.842285 (4.44 Mbytes/sec)
  CPU cycles per word for 2048 word messages is 40.407715 (6.68 Mbytes/sec)
  CPU cycles per word for 4096 word messages is 30.552979 (8.84 Mbytes/sec)
  CPU cycles per word for 8192 word messages is 25.996399 (10.39 Mbytes/sec)
  CPU cycles per word for 16384 word messages is 24.150696 (11.18 Mbytes/sec)
  CPU cycles per word for 32768 word messages is 22.350311 (12.08 Mbytes/sec)
  CPU cycles per word for 65536 word messages is 18.856659 (14.32 Mbytes/sec)
  CPU cycles per word for 131072 word messages is 17.044430 (15.84 Mbytes/sec)
  CPU cycles per word for 262144 word messages is 15.297861 (17.65 Mbytes/sec)
  CPU cycles per word for 524288 word messages is 14.353638 (18.81 Mbytes/sec)
  CPU cycles per word for 1048576 word messages is 14.093828 (19.16 Mbytes/sec)

8 Processors

  CPU cycles per word for 256 word messages is 185.888672 (1.45 Mbytes/sec)
  CPU cycles per word for 512 word messages is 121.420898 (2.22 Mbytes/sec)
  CPU cycles per word for 1024 word messages is 63.544922 (4.25 Mbytes/sec)
  CPU cycles per word for 2048 word messages is 40.275879 (6.70 Mbytes/sec)
  CPU cycles per word for 4096 word messages is 29.827881 (9.05 Mbytes/sec)
  CPU cycles per word for 8192 word messages is 27.677307 (9.76 Mbytes/sec)
  CPU cycles per word for 16384 word messages is 72.530365 (3.72 Mbytes/sec)
  CPU cycles per word for 32768 word messages is 67.504120 (4.00 Mbytes/sec)
  CPU cycles per word for 65536 word messages is 77.424774 (3.49 Mbytes/sec)
  CPU cycles per word for 131072 word messages is 62.387753 (4.33 Mbytes/sec)
  CPU cycles per word for 262144 word messages is 60.280437 (4.48 Mbytes/sec)
  CPU cycles per word for 524288 word messages is 36.552544 (7.39 Mbytes/sec)
  CPU cycles per word for 1048576 word messages is 58.031502 (4.65 Mbytes/sec)