thol...@woh.rr.com said: > Thanks to Chris, Magnus, and Trent for clearing things up. Never would have > expected going to the effort of putting in a cheap clock, only to use it very > little.
The frequency of your clock determines the granularity of a simple/quick read-the-clock operation. If you have a TSC and use it for timekeeping, you can easily get ns level results quickly and cleanly. With something like a RTC/TOY/CMOS clock you get much reduced granularity. The basic clock is only good to a second. Most of them had some mechanism to generate an interrupt every N ms. That was long used by the scheduler and for timekeeping. Then somebody used the TSC to interpolate between scheduler ticks. Then somebody did all the timekeeping from the TSC. Many years ago, I was graphing ntpd's drift vs temperature. I thought the kernel was using the TSC for timekeeping. My graphs got much cleaner when I moved the temperature probe from the CPU crystal over to the CMOS clock crystal. Many years ago. -- These are my opinions. I hate spam. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
