On precise, we had been installing cpufrequtils and letting its default "performance" setting give us the performance governor. There are two issues blocking it working correctly on the jessie cache nodes right now:

1. We're running a trunk kernel with overwritten modules, so we can't load the module (...)
2. the cpufrequtils package for jessie seems broken with our 3.19+ kernels anyways, due to a dependency on modules which were renamed.