David Woolley wrote: >> packet shows up, which with laptops I know will considerably degrade the > > I'm not convinced this is even about laptops. I think it is about PDAs, > or about embedded systems that may run for a year on a couple of AA > bateries, or may run on small photocell arrays.
I think that the lesswatts.org initiative (which should of course have been called fewerwatts.org but that's another story) is about reducing the power consumption of _all_ hardware that runs Linux, including laptops, desktops, servers, embedded devices etc. I also think that ntpd runs on a sizeable percentage of all such hardware that's in service out there. But that's not why I raised the question here. Ntpd's once-per-second interrupt is nothing compared with the hundreds-to-thousands of wakeups per second initiated by certain poorly-written hardware device drivers. I just wanted to prompt a discussion on understanding the implications of Red Hat's patch. Application writers do (I think) have a responsibility to the planet to verify/justify their application's impact on the platform's total power consumption (and the lesswatts.org website provides tools for doing that, e.g. powertop), but as I said I don't think that ntpd is an especially power-hungry application. The lesswatts.org site also mentions a range of other power-saving measures in recent Linux kernels, including the bunching together of wakeup events. Some applications have no need for very precise timers, they just want to be woken up more-or-less-2s-from-now. The kernel is then able to schedule a bunch of these imprecise timers at the same time such that the number of wakeups is minimised. Clearly ntpd does need precision and therefore probably must not use this new class of imprecise timers, but I also don't know whether anyone knows if the existence of the imprecise timers has a knock-on effect on the precision of the standard timers. On the other hand, perhaps ntpd _can_ use the imprecise timers provided it also has access to an accurate platform time stamp when the timer fires. Cheers, Jan _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
