On Wed, May 26, 2010 at 02:57:45PM +0200, Peter Zijlstra wrote: > I fail to see why. In both cases the woken userspace will contact a > central governing task, either the kernel or the userspace suspend > manager, and inform it there is work to be done, and please don't > suspend now. Thinking about this, you're right - we don't have to wait, but that does result in another problem. Imagine we get two wakeup events approximately simultaneously. In the kernel-level universe the kernel knows when both have been handled. In the user-level universe, we may have one task schedule, bump the count, handle the event, drop the count and then we attempt a suspend again because the second event handler hasn't had an opportunity to run yet. We'll then attempt a suspend and immediately bounce back up. That's kind of wasteful, although it'd be somewhat mitigated by checking that right at the top of suspend entry and returning -EAGAIN or similar. -- Matthew Garrett | mjg59@xxxxxxxxxxxxx _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
