[ntp:questions] like a kid with a new toy (PPS jitter)

Terje Mathisen "terje.mathisen at tmsw.no" at ntp.org
Fri Feb 6 07:21:19 UTC 2009


p.kennedy at fugro.com.au wrote:
> On Feb 6, 7:23 am, Dave Hart <daveh... at gmail.com> wrote:
>> It's running with a patch to lock the main and timer threads to the
>> 2nd CPU using SetThreadAffinity.  I haven't tried locking the async I/
>> O thread as well, but I will now.  It's also running with a patch to
>> the interpolation code which is more selective about baseline counter/
>> time pairs it uses.  There is a faster server on the same LAN I could
>> try as well, but I figured slower is better for understanding how bad
>> the user-mode PPS implementation is.
>>
>> Cheers,
>> Dave Hart
> 
> Under windows OS, I believe working in the 10's of microsecod range is
> pretty good, and a darn site better than flat NMEA.  Terje, can you
> let me know what is bad about this?

Oh, it is indeed _very_ good!

When I wrote my reply I simply didn't consider getting such good results 
under Windows, i.e. I assumed FreeBSD or Linux.

Mea Culpa!

Dave: You're doing great!

Terje
-- 
- <Terje.Mathisen at tmsw.no>
"almost all programming can be viewed as an exercise in caching"




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