Why did it take over 7 minutes for the CPUs to throttle up from 1600 MHz to 3400 MHz?

Child  0 lp   81 of 9999: Elapsed: 416.31 s. Delta:   5.14 s. user cpu: 387.52 s. sys cpu:   0.02 s. last sleep freq.: 194.553 Hz. average sleep freq.: 194.567 Hz.
Child  0 lp   82 of 9999: Elapsed: 421.46 s. Delta:   5.15 s. user cpu: 392.30 s. sys cpu:   0.02 s. last sleep freq.: 194.175 Hz. average sleep freq.: 194.562 Hz.
Child  0 lp   83 of 9999: Elapsed: 426.19 s. Delta:   4.73 s. user cpu: 396.68 s. sys cpu:   0.02 s. last sleep freq.: 211.416 Hz. average sleep freq.: 194.749 Hz.
Child  0 lp   84 of 9999: Elapsed: 428.56 s. Delta:   2.37 s. user cpu: 398.70 s. sys cpu:   0.02 s. last sleep freq.: 421.941 Hz. average sleep freq.: 196.005 Hz.
Child  0 lp   85 of 9999: Elapsed: 430.93 s. Delta:   2.37 s. user cpu: 400.72 s. sys cpu:   0.02 s. last sleep freq.: 421.941 Hz. average sleep freq.: 197.248 Hz.
Child  0 lp   86 of 9999: Elapsed: 433.30 s. Delta:   2.37 s. user cpu: 402.73 s. sys cpu:   0.02 s. last sleep freq.: 421.941 Hz. average sleep freq.: 198.477 Hz.


Child  1 lp   81 of 9999: Elapsed: 416.56 s. Delta:   5.14 s. user cpu: 387.73 s. sys cpu:   0.05 s. last sleep freq.: 194.553 Hz. average sleep freq.: 194.450 Hz.
Child  1 lp   82 of 9999: Elapsed: 421.71 s. Delta:   5.15 s. user cpu: 392.52 s. sys cpu:   0.05 s. last sleep freq.: 194.175 Hz. average sleep freq.: 194.446 Hz.
Child  1 lp   83 of 9999: Elapsed: 426.27 s. Delta:   4.56 s. user cpu: 396.73 s. sys cpu:   0.05 s. last sleep freq.: 219.298 Hz. average sleep freq.: 194.712 Hz.
Child  1 lp   84 of 9999: Elapsed: 428.64 s. Delta:   2.37 s. user cpu: 398.75 s. sys cpu:   0.05 s. last sleep freq.: 421.941 Hz. average sleep freq.: 195.969 Hz.
Child  1 lp   85 of 9999: Elapsed: 431.01 s. Delta:   2.37 s. user cpu: 400.77 s. sys cpu:   0.05 s. last sleep freq.: 421.941 Hz. average sleep freq.: 197.211 Hz.
Child  1 lp   86 of 9999: Elapsed: 433.38 s. Delta:   2.37 s. user cpu: 402.79 s. sys cpu:   0.05 s. last sleep freq.: 421.941 Hz. average sleep freq.: 198.440 Hz.

It seems as though it is some other event that stimulates things such the CPUs finally throttle up. For example some cron job or some other command on some other terminal.

These CPUs were over 90% busy. Why didn't they throttle up almost immediately after being placed under heavy load? Answer: Because the up_threshold is 95%.
see: /sys/devices/system/cpu/cpufreq/ondemand/up_threshold