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
1202.68 ms
total CPU used
5473.15 ms
speedup
4.55×
vs serial
efficiency
91%
of 5× ideal
stream spawn ms spawned@ work start@ work end@ work ms reap wait ms
0 (main) 0 9.74 9.75 1145.55 1135.8 0
1 1.978 2 14.76 1145.25 1130.49 0.1
2 1.706 3.73 17.05 1025.56 1008.51 2.75
3 1.56 5.32 19.29 1046.23 1026.94 2.77
4 4.403 9.74 28.33 1199.74 1171.41 54.36
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.