CPU scaling benchmark
workers
2 +1 main
iters total
500M
166666666/stream
elapsed
1468.08 ms
total CPU used
4335.31 ms
speedup
2.95×
vs serial
efficiency
98.3%
of 3× ideal
| stream | spawn ms | spawned@ | work start@ | work end@ | work ms | reap wait ms |
|---|---|---|---|---|---|---|
| 0 (main) | 0 | 3.24 | 3.26 | 1443.5 | 1440.24 | 0 |
| 1 | 1.787 | 1.8 | 15.62 | 1461.89 | 1446.27 | 18.53 |
| 2 | 1.406 | 3.23 | 16.57 | 1465.37 | 1448.8 | 22.32 |
main
w1
w2
fork+handshake
CPU work
parent reap wait
what this measures
Each stream runs a tight integer LCG loop — working set is one CPU register, no memory access,
no shared data. Speedup = sum(stream CPU time) / wall-clock elapsed. Efficiency = speedup / (workers+1).
100% efficiency means perfect linear scaling; less than 100% is the cost of serial fork setup,
reap tail, SMT/core contention.