Re: Attempted summary of suspend-blockers LKML thread
From: david
Date: Tue Aug 03 2010 - 01:07:54 EST
On Mon, 2 Aug 2010, Arve Hj?nnev?g wrote:
2010/8/2 <david@xxxxxxx>:
On Mon, 2 Aug 2010, Arve Hj?nnev?g wrote:
On Mon, Aug 2, 2010 at 5:08 PM, <david@xxxxxxx> wrote:
On Mon, 2 Aug 2010, Paul E. McKenney wrote:
you are close, but I think what I'm proposing is actually simpler
(assuming
that the scheduler can be configured to generate the appropriate stats)
my thought was not to move applications between cgroups as they
aquire/release the suspend-block lock, bur rather to say that any
application that you would trust to get the suspend-block lock should be
in
cgroup A while all other applications are in cgroup B
when you are deciding if the system shoudl go to sleep because it is
idle,
ignore the activity of all applications in cgroup B
if cgroup A applications are busy, the system is not idle and should not
suspend.
Triggering suspend from idle has been suggested before. However, idle
is not a signal that it is safe to suspend since timers stop in
suspend (or the code could temporarily be waiting on a non-wakeup
interrupt). If you add suspend blockers or wakelocks to prevent
suspend while events you care about are pending, then it does not make
a lot of sense to prevent suspend just because the cpu is not idle.
isn't this a matter of making the suspend decision look at what timers have
been set to expire in the near future and/or tweaking how long the system
needs to be idle before going to sleep?
You are describing low power idle modes, not suspend. Most timers stop
in suspend, so a timer set 10 seconds from now when entering suspend
will go off 10 seconds after resume so it should have no impact on how
long you decide to stay in suspend.
so what is the fundamental difference between deciding to go into
low-power idle modes to wake up back up on a given point in the future and
deciding that you are going to be idle for so long that you may as well
suspend until there is user input?
David Lang