> That's correct, but to me the Arve's goal is simply to maximize battery life > and he found experimentally that the longest battery life is achieved if > system suspend is used whenever the system doesn't need to be active (from its > user's perspective). This actually is different from "when the system is > idle", because the system isn't idle, for example, when updatedb is running. > However, from the user's perspective the updatedb process doesn't really need > to run at this particular time, it can very well do it's job in parallel with > the user typing or reading news. So, the system may very well be suspended > when updatedb is running. This is where the original questions around QoS came in > Since I think we've now rejected the feature, do we have a clear picture about > what the Android people should do _instead_ and yet keep the battery life they > want? Because I don't think telling "let them do what they want, who cares" > is right. Today "idle" means "no task running" If you are prepared to rephrase that as "no task that matters is running" what would need to answer ? - How do we define who matters: QoS ? - Can you describe "idle" in terms of QoS without then breaking the reliable wakeup for an event (and do you need to ?) Could this for example look like Set QoS of 'user apps' to QS_NONE Button pushed Button driver sets QoS of app it wakes to QS_ABOVESUSPEND That would I think solve the reliable wakeup case although drivers raising a QoS parameter is a bit unusual in the kernel. That would at least however be specific to a few Android drivers and maybe a tiny amount of shared driver stuff so probably not unacceptable. (wake_up_pri(&queue, priority); isn't going to kill anyone is it - especially if it usually ignores the priority argument) I am curious Thomas how that would tie in with PI in the RT world, it's effectively inheriting priority from the users finger. - Would a model where the UI side behaviour looked like Timeout Screen Off Set QoS of 'user apps' to QS_NONE Event [Some chain of activity] Screen On Set QoS of 'user apps' to QS_ABOVESUSPEND do the job combined with the ability to see who is stopping us dropping to suspend so user space can take action. This could be a data table from the Android cpu manager provided to Android specific policy in whoever owns the display. If so how do we fix the UI policy code doing Screen Off Button Press task to QS_ABOVESUSPEND task to QS_NONE without touching the app userspace code Perhaps count2 = tasks to QS_NONE | QS_NOTCHANGED Screen off Button Press task to QS_ABOVESUSPEND count = tasks that are QS_NOTCHANGED to QS_NONE if (count != count2) { Stuff happened ... rethink } That is still a bit weird and wonderful but all the logic is in the right places. The special magic remains in the Android policy code and in the kernel specifics for Android. Thoughts ? -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html