On Tuesday 17 February 2009, Alan Stern wrote: > On Tue, 17 Feb 2009, Rafael J. Wysocki wrote: > > > Phase 1: I agree that system-auto-suspend-on, system-auto-suspend-off would be > > useful, but I don't like the wakelocks interface. Do you think there is an > > alternative way/mechanism of doing this? > > I rather like the suggestions Matthew Garrett has been making. They > show how to improve the wakelock interface without losing any function. > > Really, the idea behind wakelocks comes down to the question of how to > determine when the system is sufficiently idle to go into auto-suspend. > There may be occasions when no task is runnable but userspace knows > that the system should not go to sleep because some work will be done > in the near future. (Arve's example of a non-empty input buffer is > such a case.) How should userspace let the kernel know whether it's > okay to suspend at these times? That is the problem userspace > wakelocks are meant to solve. Still, do we really need multiple user space wakelocks (I'd prefer to call them sleeplocks)? It seems that one such lock and a user space manager controlling it should be sufficient. > Kernel wakelocks are a separate matter. They are more like a form of > optimization, preventing the kernel from starting an auto-suspend when > some driver knows beforehand that it will return -EBUSY. I think kernel-side autosuspend (or rather autosleep) should only happen after certain subset of devices have been suspended using a per-device run-time autosuspend mechanism. > > Phase 3: Probably explicit control left to open/close. > > While that's generally a good idea, it's important to recognize that > some devices should be runtime-suspended even while they are open. >From the kernel side, yes (and that should be transparent to the user space having them open). By the user space, no. > Basically, any device that is "always open" falls in this category. > Some examples are the screen, the keyboard, the mouse, and disk drives. > And of course, some of these things already have runtime power > management. Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
