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
6 +1 main
iters total
500M
71428571/stream
elapsed
1206.4 ms
total CPU used
7526.08 ms
speedup
6.24×
vs serial
efficiency
89.1%
of 7× ideal
stream spawn ms spawned@ work start@ work end@ work ms reap wait ms
0 (main) 0 11.28 11.29 1061.78 1050.49 0
1 1.573 1.59 15.55 1023.68 1008.13 0.1
2 1.428 3.04 15.11 1068.28 1053.17 9.24
3 1.492 4.54 16.67 1110.55 1093.88 49.96
4 3.979 8.53 40.48 1203.4 1162.92 141.71
5 1.364 9.91 39.73 1197.5 1157.77 135.88
6 1.351 11.27 43.4 1043.12 999.72 0.16
main
w1
w2
w3
w4
w5
w6
    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.