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
4 +1 main
iters total
500M
100000000/stream
elapsed
1165.69 ms
total CPU used
5333.14 ms
speedup
4.58×
vs serial
efficiency
91.6%
of 5× ideal
stream spawn ms spawned@ work start@ work end@ work ms reap wait ms
0 (main) 0 7.91 7.91 1074.33 1066.42 0
1 1.922 1.94 15.8 993.45 977.65 0.11
2 1.493 3.45 21.49 1162.99 1141.5 88.78
3 1.414 4.88 18.68 1110.92 1092.24 36.73
4 2.997 7.9 21.5 1076.83 1055.33 2.67
main
w1
w2
w3
w4
    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.