Messages in this thread | | | Date | Sat, 7 Feb 2009 10:20:21 +0100 | From | Pavel Machek <> | Subject | Re: [RFC] Dynamic Tick and Deferrable Timer Support |
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On Thu 2009-01-29 09:36:00, john stultz wrote: > On Thu, Jan 29, 2009 at 8:29 AM, Jon Hunter <jon-hunter@ti.com> wrote: > > Pallipadi, Venkatesh wrote: > > I have spent several weeks trying to suppress kernel timers using the > > deferred timers and lengthen the sleep time. I am now able to get the device > > to sleep for minutes but I found that max_delta_ns is a limiting factor. I > > will be surprised if you can sleep for longer than ~2.15 seconds with the > > current implementation. > > As an aside, there are some further hardware limitations in the > timekeeping core that limit the amount of time the hardware can sleep. > For instance, the acpi_pm clocksource wraps every 2.5 seconds or so, > so we have to wake up periodically to sample it to avoid wrapping > issues. > > Just to be able to deal with all the different hardware out there, the > timekeeping core expects to wake up twice a second to do this > sampling. It may be possible to push this out if you are using other
That's strange... I think I seen less than 2 wakeups per second on powertop...? (thinkpad x60, nothing exotic). Pavel
-- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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