On Wednesday 19 May 2010, Arve Hjønnevåg wrote: > 2010/5/18 Rafael J. Wysocki <rjw@xxxxxxx>: > > On Wednesday 19 May 2010, Arve Hjønnevåg wrote: > >> 2010/5/18 Rafael J. Wysocki <rjw@xxxxxxx>: > >> > On Tuesday 18 May 2010, Arve Hjønnevåg wrote: > >> >> 2010/5/18 Rafael J. Wysocki <rjw@xxxxxxx>: > >> >> > On Tuesday 18 May 2010, Arve Hjønnevåg wrote: > >> >> >> On Mon, May 17, 2010 at 2:44 PM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > >> >> >> > On Monday 17 May 2010, Brian Swetland wrote: > >> >> >> >> On Mon, May 17, 2010 at 1:40 PM, Rafael J. Wysocki <rjw@xxxxxxx> wrote: > >> >> >> >> > On Monday 17 May 2010, Arve Hjønnevåg wrote: > >> >> >> >> >> > >> > ... > >> >> > >> >> > Now, to make it more "user-friendly", we can simply use > >> >> > queue_delayed_work() with a reasonable delay instead of queue_work() to queue > >> >> > the suspend work (the delay may be configurable via sysfs). > >> >> > > >> >> > >> >> I can add a delay (and the timeout support code does add a delay as an > >> >> optimization) to the unknown wakeup case, but this does not fix the > >> >> problem of a user turning on opportunistic suspend with a user space > >> >> framework that does not use suspend blockers. If the kernel uses > >> >> suspend blockers to make sure the wakeup event makes it to user space, > >> >> but user space does not block suspend, then the system will suspend > >> >> before the event is processed. > >> > > >> > But the user can still manually write to /sys/power/state. :-) > >> > > >> > >> Does adding or removing a delay change this? It seems in only changes > >> how quickly the user can finish that write. > > > > Yes, but that should allow the user to avoid rebooting the system if he does > > the "wrong thing". > > > >> I'm not convinced adding a configurable delay here is necessary. > > > > No, it's not, but it would be useful in some cases IMO. Pretty much the same > > way your debug features are useful. > > > >> Once the driver that enabled the wakeup event has been updated to block > >> suspend until this event gets to user space, then this delay will > >> never be triggered. The kernel cannot tell the difference between a > >> user enabling opportunistic suspend but not wanting it and > >> opportunistic suspend aware user space code deciding that this wakeup > >> event should be ignored. > > > > The point is, if there's a delay, it may be too aggressive for some users and > > too conservative for some other users, so it makes sense to provide a means > > to adjust it to the user's needs. > > > > My point is that the delay will not be used at all if the driver uses > a suspend blocker (like it should). Why add a configuration option for > opportunistic suspend that only works when the driver does not support > opportunistic suspend. Because on many systems there are no such drivers (yet, at least). Rafael _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
