Improvement in Wallclock Time
Persistent vs. Conventional Communication
| msize (bytes) |
mode |
improvement |
mode |
improvement |
| 8 |
async |
19 % |
sync |
15 % |
| 4096 |
async |
11 % |
sync |
4.7 % |
| 8192 |
async |
5.9 % |
sync |
2.9 % |
| 800,000 |
- |
- |
sync |
0 % |
| 8,000,000 |
- |
- |
sync |
0 % |
These timings were made with a very simple Fortran program in which, within a loop, one task repeatedly sends a message to a second task. For the three smaller message sizes, the number of loop iterations was varied between 10,000 and 1,000,000. The improvement with persistent communication did not vary with number of loop iterations, or for sends vs receives.
Measurements were made for asynchronous and synchronous communication. All asynchronous communication was measured using standard mode.
