In article <41FE23F1.6080908@cql.com>, Seth Kurtzberg
Doesn't automatically forcing a system clock tick screw up the time?
Well, one nanosecond is three cycles of a 3GHz processor. For the time being it seems unlikely to be a problem.
Also, what happens when you are using NTP? NTP might just correct it, but it would screw up the calculations NTP uses and it could start oscillating.
NTP knows all about this, and it's only an issue with leap seconds. See http://www.eecis.udel.edu/~mills/leap.html
I don't think we disagree, in general, it's more a question of whether or not system clock related computations should match the precision of the system clock. 123.45000 implies that the value is known to be accurate to five decimal points (just picking an arbitrary number of digits beyond the decimal point, because I don't recall the actual precision of the high resolution library). Truncating at the end is also not "correct," because the final result in general might be different if you compute with five digits and truncate, rather than computing with two digits throughout. (Again, whatever the number is; I pulled 2 digit out of the air, just to use a number.)
To me all this shows that the system clock needs to be handled as a special case, not just converted into the high resolution representation
The system clock gives measurements with a particular accuracy attached. This isn't a particularly special case, other time applications may involve measurements or calculations to some particular accuracy. -- Ashley Yakeley, Seattle WA