Daniel Walker wrote:
On Thu, 20 Oct 2005, Steven Rostedt wrote:
Yes, but that shouldn't make a difference. NTP can slow down or speed up
the clock, but it should never make it go backwards. Especially for a
monotonic clock (as the name suggests).
It looks like if ntp_adj held a big negative number you might end up
with a smaller output . ntp_adj is signed too .. I don't know how
ntp_adj is set though .
I thought I remember George Anzinger speculating that ntp could
cause the time to backwards , that's why I brought it up. Maybe if he's
read he can clue us in ..
I think John has changed this, but in the "old" code if ntp was correcting the clock such that less
than TICK_NSEC was added on a tick, AND, the time was read just prior to this tick the get_offset
code would return ~TICK_NSEC of offset which would mean that a read right after the tick might be
less than the one just prior to the tick. The error, however, would be in the nanosecond area (no
where near a second). Again, as I said, I think John has changed this in is code so that the
get_offset equivalent is also ntp corrected, thus eliminating the small back step.
--
George Anzinger [email protected]
HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/
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