2010/5/27 Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>: > On Thu, May 27, 2010 at 04:36:28PM -0700, Arve Hjønnevåg wrote: >> 2010/5/27 Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>: >> > On Wed, May 26, 2010 at 05:52:40PM -0700, Arve Hjønnevåg wrote: >> >> 2010/5/26 Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>: >> >> > On Wed, 26 May 2010, Arve Hjønnevåg wrote: >> >> > >> >> >> > I must be missing something. In Arve's patch 1/8, if the system is in >> >> >> > opportunistic suspend, and a wakeup event occurs but no suspend >> >> >> > blockers get enabled by the handler, what causes the system to go back >> >> >> > into suspend after the event is handled? Isn't that a loop of some >> >> >> > sort? >> >> >> > >> >> >> >> >> >> Yes it is a loop. I think what you are missing is that it only loops >> >> >> repeatedly if the driver that aborts suspend does not use a suspend >> >> >> blocker. >> >> > >> >> > You mean "the driver that handles the wakeup event". I was asking what >> >> > happened if suspend succeeded and then a wakeup occurred. But yes, if >> >> > a suspend blocker is used then its release causes another suspend >> >> > attempt, with no looping. >> >> > >> >> >> > And even if it isn't, so what? What's wrong with looping behavior? >> >> >> >> >> >> It is a significant power drain. >> >> > >> >> > Not in the situation I was discussing. >> >> > >> >> >> >> If you meant it spend most of the time suspended, then I agree. It >> >> only wastes power when a driver blocks suspend by returning an error >> >> from its suspend hook and we are forced to loop doing no useful work. >> >> >> > >> > If driver refuses to suspend that means there are events that need >> > processing. I fail to see why it would be called "looping doing no >> > useful work". >> >> Because the useful work is done in another thread. All the loop does >> is check if the useful work has completed which most likely will slow >> down the useful work. > > Or useful work could signal when it is done processing critical section. > That is what suspend_unblock does. >> Blocking suspend with a suspend blocker until >> the useful work is done is more efficient. >> > > -- > Dmitry > -- Arve Hjønnevåg _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
