CPU scaling benchmark

W=0 W=1 W=2 W=3 W=4 W=6 W=8 W=9 W=10 W=12 W=16 iters: 100M 500M 1B 2B
workers
8 +1 main
iters total
500M
55555555/stream
elapsed
1155.5 ms
total CPU used
9067.35 ms
speedup
7.85×
vs serial
efficiency
87.2%
of 9× ideal
stream spawn ms spawned@ work start@ work end@ work ms reap wait ms
0 (main) 0 12.82 12.83 980.17 967.34 0
1 1.827 1.84 16.13 1122.52 1106.39 142.47
2 1.47 3.33 29.41 846.26 816.85 0.11
3 1.478 4.83 27.84 1125.62 1097.78 145.56
4 1.457 6.3 38.85 1097.04 1058.19 117.02
5 1.421 7.74 42.52 1103.88 1061.36 131.96
6 1.512 9.37 33.82 960.65 926.83 0.17
7 1.858 11.24 58.82 1152.88 1094.06 172.83
8 1.537 12.8 45.29 983.84 938.55 9.13
main
w1
w2
w3
w4
w5
w6
w7
w8
    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.