Compare iteration over individual agent objects with SIMD operation on the relevant data.
| Sample output from Intel Xeon E5-2630 @ 2.3GHz | "brute force" | SIMD | speedup |
|---|---|---|---|
| Total infectivity | 182821.078125 | 182837.437500 | n/a |
| Attenuate (ms) | 252.352506 | 3.145453 | 80x |
| Sum (ms) | 12.075272 | 0.220914 | 55x |
This is working on 220 agents/values.
The attenuate step (multiply by 0.9 ten times) is ~80x faster with SIMD. The sum step is 50x-60x faster with SIMD (more variability in timing with the shorter duration).
The results differ because the SIMD operation uses 8 parallel accumulators which don't lose precision as quickly. The SIMD result is, technically, more correct.