On Tue, 10 Aug 2010, Matthew Garrett wrote: > On Tue, Aug 10, 2010 at 09:38:49AM +0100, Alan Cox wrote: >>> Hmmm... Exactly which part do you consider flawed? Let's take it >>> one sentence at a time. The devices that I know of that lack suspend >>> blockers also lack opportunistic suspend. Therefore, all applications on >>> such devices run as would an application that acquired a suspend blocker >>> when it started and did not release that suspend blocker until it exited. >>> Pretty straightforward. >> >> What do you mean by "opportunistic suspend", lots of systems drop into >> lowest power states whenever they can. "Suspend is different" is a bit of >> Android religion that I am dubious has any basis in reality as seen from >> the application end of the universe. >> >> You may also wish to review the earlier parts of the discussion where it >> was explicitly stated by several developers that they were using >> "suspend" type modes as power states already and not using suspend >> blockers. So it's being done, today on ARM and your statement is directly >> contradicting the code. Modern ARM processors and x86 MID devices can >> suspend and resume extremely fast (fast enough that the fact Linux x86 >> rewriting all the SMP alternatives on suspend/resume is a measurable >> problem). If this same property doesn't end up on big PC boxes in time >> then I'd be very surprised. At that point the openoffice with suspend >> blockers or oracle with suspend blockers question becomes rather relevant. > > There's a clear and absolute difference between system suspend and > entering the same hardware state from the idle loop. That difference is > that processes aren't scheduled until an explicit wakeup event occurs. > Android is entirely capable of entering the same low power state at idle > (it's done with a hardcoded idle loop on Qualcomm, cpuidle on omap), but > if you have more than 0 scheduling wakeups a second then your power draw > is going to be greater. > > I agree that we should be targetting 0 wakeups per second. I don't agree > that it's realistic to insist that a use model that assumes imperfect > software is an invalid use model. If the primary difference between sleep and suspend is not scheduling processes, instead of messing with oppurtinistic suspend/suspend blockers/wakelocks/etc, why not just 'temporarily' change the timer fuzz value to a very large value (say an hour). That would still let things like openoffice saves ahve a fair chance to trigger before the battery died completely, but would wake the system so infrequently that it will be effectivly the same as a full suspend. David Lang _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
