[ntp:questions] Re: How application get precise time from Win NT/XP system time that synchronies to NTP

David Woolley david at djwhome.demon.co.uk
Sun Mar 27 08:15:58 UTC 2005

In article <m3y8ca6rwi.fsf at lysator.liu.se>,
Bjorn Gabrielsson <bg at lysator.liu.se> wrote:

> True if you need that accuracy 99.9999% of the samples. If 95-98% is

I would hope that anyone aware enough of the issues would have specified
the percentile that had to be within 10 microseconds.  To me, not
specifying it suggests that they really expect to get 100% of 
measurements within that limit.

> enough, I have done it on Linux with the TIOCMIWAIT ioctl. I got
> inspiration from Jonathan Buzzards radioclkd. phk has an excellent

We are not talking about timestamping NTP messages or PPS but about
timestamping something (currently unspecified) in the application domain.
One has to assume that there are some inbound events, in which case 
interrupts is the only way of getting close on a general purpose OS, but
we don't know what device is interrupting.

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