Speaker
Description
At the last LPC, we discussed PM QoS. However, the implementation proposed this year did not reach consensus; the semantics of PM QoS are perceived differently.
The proposal was for in-kernel actors and userspace to vote on a constraint. Once a constraint is set, if the userspace process exits, the constraint is automatically removed provided no other actors hold the same constraint. When the last actor releases the constraint, it is removed automatically.
Rather than debating PM QoS itself, it may be preferable to step back and revisit the approach: provide a generic mechanism for voting on a specific value. PM QoS could then be built on top of that and define its own units for the voted value (watts, kbps, performance level, etc.).
The talk and subsequent discussion are about defining the semantics of such a voting mechanism—for example, does a kernel vote have higher priority than a userspace vote, or do we want to support out-of-band votes?