Battery Life
The changes discussed above will also affect battery life. Disabling the thread migration boost feature should provide a net power savings. Having all four cores active means less CPU pressure, so the governor can keep individual core frequencies lower on average, again reducing dynamic CPU power. Of course keeping those extra two cores online will increase static power draw due to leakage, offsetting some of the battery life gains.
Battery Benchmarks
| Benchmark | Nexus 6Android 5.0 | Nexus 6Android 5.1 | Difference | |
|---|---|---|---|---|
| GFXBench 3.0 | Performance | 19.5 fps | 21.0 fps | 7.40% |
| Lifetime | 181 min | 175.5 min | -3.04% | |
| PCMark | Work Battery Life | 329 min | 354 min | 7.45% |
Battery life is generally difficult to quantify due to the huge variation in potential workloads, and becomes even more difficult when trying to assess the impact of the specific changes included in the 5.1 update. The best test we have for this is PCMark, which performs a few common tasks instead of purely synthetic loops. Here we see more than a 7% gain in battery life, which equates to a noticeable 25 minutes of runtime.