On Wednesday, August 04, 2010, Matthew Garrett wrote: > On Wed, Aug 04, 2010 at 11:30:44AM -0700, david@xxxxxxx wrote: > > a couple days ago I made the suggestion to put non-privilaged tasks in a > > cgroup so that the idle/suspend decision code could ignore acitivity > > caused by this cgroup. > > > > in the second version wakeup events would be 'activity' that would be > > counted and therefor the system would not be idle. As for the race with > > suspending and new things happening, wouldn't that be handled the same > > way that it is in a normal linux box? > > No! And that's precisely the issue. Android's existing behaviour could > be entirely implemented in the form of binary that manually triggers > suspend when (a) the screen is off and (b) no userspace applications > have indicated that the system shouldn't sleep, except for the wakeup > event race. Imagine the following: > > 1) The policy timeout is about to expire. No applications are holding > wakelocks. The system will suspend providing nothing takes a wakelock. > 2) A network packet arrives indicating an incoming SIP call > 3) The VOIP application takes a wakelock and prevents the phone from > suspending while the call is in progress > > What stops the system going to sleep between (2) and (3)? cgroups don't, > because the voip app is an otherwise untrusted application that you've > just told the scheduler to ignore. I _think_ you can use the just-merged /sys/power/wakeup_count mechanism to avoid the race (if pm_wakeup_event() is called at 2)). Thanks, Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
