Androids: The Team That Built the Android Operating System

by Chet Haase

A governor in an OS is the mechanism by which the speed, or frequency, of the CPU is changed to save power. For example, if your CPU is running really fast, then it is consuming more power and thus more battery. But if the device is idle at the time, that’s a large and unnecessary waste of battery power. The governor exists to detect these different runtime modes and scale the CPU frequency accordingly. When the G1 launched, the only governor in effect was the ondemand governor that was part of core Linux. It was a simple system with just two settings: full-speed and idle. This was better than nothing, but wasn’t good enough for Android’s purposes, especially since the heuristics for that governor were tuned for Linux running on server or desktop machines, not for the more constrained world of mobile devices. Mike started playing with the governor in the late stages of 1.0, but had to put that project aside after an unfortunate incident of a demo that Andy gave to the Google execs. Mike had checked in a change that inadvertently made the phone painfully slow. “I was experimenting on master101 with the conservative governor, which skewed very, very heavy towards saving power at the cost of performance. The phone was pretty much unusable.” Meanwhile, Andy had a monthly review with Larry and Sergey to show them the status of this project. Andy flashed102 a build of master onto a phone and went off to his meeting. At the meeting, he showed a demo using that build, which… did n...