Linux Plumbers Conf 2013

“As mobile and embedded processors get more complex — and more numerous — the interest in improving the power efficiency of the scheduler has increased. While a number of power-related scheduler patches exist, none seem all that close to merging into the mainline. Getting something upstream always looked like a daunting task; scheduler changes are hard to make in general, these changes come from a constituency that the scheduler maintainers are not used to serving, and the existence of competing patches muddies the water somewhat. But now it seems that the complexity of the situation has increased again, to the point that the merging of any power-efficiency patches may have gotten even harder.The current discussion started at the end of May, when Morten Rasmussen posted some performance measurements comparing a few of the existing patch sets. The idea was clearly to push the discussion forward so that a decision could be made regarding which of those patches to push into the mainline. The numbers were useful, showing how the patch sets differ over a small set of workloads, but the apparent final result is unlikely to be pleasing to any of the developers involved: it is entirely possible that none of those patch sets will be merged in anything close to their current form, after Ingo Molnar posted a strongly-worded “line in the sand” message on how power-aware scheduling should be designed.”

The mission for this MC is to work towards an acceptable power-aware scheduling solution. Discussions about issues faced by current and emerging platforms are needed to identify the design requirements. This includes integration with related power management frameworks (cpuidle, cpufreq). Agreeing on the path ahead is essential for reaching a unified solution.