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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 george@mvista.com HRT (High-res-timers): http://sourceforge.net/projects/high-res-timers/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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