CPU usage used to hover around 30%, +/- 2%

Recently (around R56-8932.0) CPU usage become a bit more erratic; varying in the range (25-35%).

In the range R56-8979.0 .. R57-9016.0, CPU usage shot up to ~62% for many runs.

Recently (R57-9020.0 .. R57-9038.0) the CPU usage has dropped back down to ~30 % - however, the data is quite sparse due to many missing build results.

https://cros-goldeneye.corp.google.com/console/listCrosbolt?baselineMilestoneChannel=56%20%3A%20DEV&comparisonMilestoneChannel=57%20%3A%20DEV&analysisType=BUILD_TO_BUILD&selectedDevices=elm_cpu_mtk_4core_18g_4Gb


The initial "erratic" behavior seems to correspond to enabling cpusets, which landed in 8931.0.0, so hopefully jcliang can investigate a bit:
https://chromium-review.googlesource.com/#/c/401073/