Re: [chrony-users] Using Chrony with a DS3231 RTC without RTC_UIE_ON

[Hal Murray <hmurray@xxxxxxxxxxxxxxx>]

mlichvar@xxxxxxxxxx said:
> It seems hwclock has a fallback to handle RTCs without interrupts by reading
> the RTC time in a busy loop. I don't think that would be acceptable for
> chronyd to consume 100% of a CPU core just to track an RTC. 

The RTC is a clock rather than a source of arbitrary pulses.  You should be 
able to predict when it will tick and start polling a bit before that.  It 
would be an interesting experiment to see how much CPU it takes and/or how 
accurately you can locate the ticks.

Note that if you guess wrong (aka late) you can stop spinning after a short 
while and try again for the next tick.

If you have no idea when it will tick, you can probably do a binary search.


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