2010/6/4 Peter Zijlstra <peterz@xxxxxxxxxxxxx>: > On Fri, 2010-06-04 at 01:56 -0700, Arve Hjønnevåg wrote: >> On Fri, Jun 4, 2010 at 1:34 AM, Ingo Molnar <mingo@xxxxxxx> wrote: >> > >> > * Arve Hj?nnev?g <arve@xxxxxxxxxxx> wrote: >> > >> >> > [...] >> >> > >> >> > Why do you need to track input wakeups? It's rather fragile and rather >> >> > unnecessary [...] >> >> >> >> Because we have keys that should always turn the screen on, but the problem >> >> is not specific to input events. If we enabled a wakeup event it usually >> >> means we need this event to always work, not just when the system is fully >> >> awake or fully suspended. >> > >> > Hm, i cannot follow that generic claim. Could you please point out the problem >> > to me via a specific example? Which task does what, what undesirable thing >> > happens where, etc. >> > >> >> We have many wakeup events, and some of them are invisible to the >> user. For instance on the Nexus One wake up every 10 minutes monitor >> the battery health. > >> If the user presses a key right after this work >> has finished and we did not block suspend until userspace could >> process this key event, we risk suspending before we could turn the >> screen on, which to the user looks like the key did not work. > >> Another >> example, the user pressed the power key which turns the screen off and >> allows suspend. We initiate suspend and a phone call comes in. If we >> don't block suspend until we processed the incoming phone call >> notification, the phone may never ring (some devices will send a new >> message every few seconds for this, so on those devices it would just >> delay the ringing). > > Right, so in the proposed scheme all these tasks would be executed by > trusted processes, and trusted processes will never get frozen and so > will never be delayed in processing these events. > There are many proposes schemes. I assume you mean freezing only untrusted processes and nothing else. > Only untrusted code will be frozen. And trusted processes are reliable > for thawing the untrusted processes and delivering events to it. > I have two problems with this. I don't want to funnel all events trough trusted processes, and I also want to freeze trusted processes. > Trusted processes are assumed to be sane and idle when there is nothing > for them to do, allowing the machine to go into deep idle states. > Neither the kernel nor our trusted user-space code currently meets this criteria. -- Arve Hjønnevåg -- 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
