[ntp:questions] ntp-4.2.6p5 on Win 7 x64
me at privacy.net
Thu Jul 24 16:44:41 UTC 2014
On Thu, 24 Jul 2014 12:14:21 +0200, Martin Burnicki wrote:
> Have you also tested without -M switch?
I will do. There are a number of test cases I want to try.
>> What makes ntpd think that the frequency error on Windows is +493?
> From my experience such frequency error under Windows is simply wrong
> because the time stamps read from the system time provide too much
Yes. I deleted ntp.drift and the error went down to 125. Just deleted it
again and it's dropped to -19.
> What's the output of "ntpq -p" in this case? I'm assuming the numbers
> both for jitter and offset are very large, eventually more than 1000 ms.
>> wclkres64 reports that performance counter frequency is 2.734MHz. The
>> QPC execution time for 1000 calls varies between 26ns and 37ns.
> This should only matter at all if ntpd interpolates the system time
> using APC timer callbacks and QPC calls.
> ntpd-dev should not use interpolation at all if it detects that the
> system time increments in 1 ms steps. If interpolation is *not* used
> then after startup of the NTP service there should be a message in the
> Windows application event log reading "using windows clock directly".
Yes I see that message with the -M switch.
I had a look at the DPC latency which was regularly peaking over 10ms.
Disabled the index service which improved things. Although all the power
management in the BIOS is disabled I set Power Management, Minimum
Processor State to 100% and all the DPC delays disappeared. I also
updated the BIOS and the motherboard drivers, just in case.
NTP now works a bit better. Reach gets to 377 and stays there. Offsets
and jitters are now in the 10's of ms rather than 100's or 1000's.
I know there's more to be had from it because I see offsets and jitters
in the low ms on XP.
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