[time-nuts] Cheap jitter measurements

Hal Murray hmurray at megapathdsl.net
Tue Apr 10 18:41:41 EDT 2018


Gary said:
>> The API  for the kernel clock can be read to a ns.  I don't see ntpd
>> having much use for finer grain than that.  I should look at the
>> source to see what the internal details look like.

> Yeah, but the granularity is much worse.

Do you have code that demonstrates that?  (or tell me how and I'll try it)

I think most modern kernels derive time from a cycle-count register.  So the 
basic clock should be accurate to a cycle.  Yes, that's worse than a ns on 
slow CPUs.

-- 
These are my opinions.  I hate spam.






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