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
1256.66 ms
total CPU used
5325.22 ms
speedup
4.24×
vs serial
efficiency
84.8%
of 5× ideal
stream spawn ms spawned@ work start@ work end@ work ms reap wait ms
0 (main) 0 6.73 6.74 1033.73 1026.99 0
1 1.933 1.95 18.25 1253.92 1235.67 220.33
2 1.667 3.64 23.84 990.37 966.53 0.1
3 1.505 5.17 19 1073.44 1054.44 39.83
4 1.521 6.71 37.21 1078.8 1041.59 45.19
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.