On Sun, Feb 5, 2012 at 01:54, Ron Frazier (NTP) <[email protected]> wrote: > I thought there was a way to override the application's built in priority > selection, other than using task manager.
You may be referring to a command-line option to raise the priority. That option makes a difference for ntpd on most platforms, but on Windows it always raises to realtime (or high if lacking privilege). > I may have to try the method you > mentioned if my testing indicates it's necessary. Here's why I think it may > be a problem. Take a look at the following loopstats file: > > http://dl.dropbox.com/u/9879631/loopstats.20120129p08-3-real-priority > > Note that is has a number of discrepancies and jaggedy areas and > discontinuities along the time axis.. It also has a maximum excursion of > around 30 ms offset. > > Now look at this file: > > http://dl.dropbox.com/u/9879631/loopstats.20120203p08-3-above-priority > > This is representative of what I've been getting from my USB GlobalSat > BU-353 when I have it set on Above Normal priority after switching it with > the task manager away from real time priority. Note that the scales are > different if you chart it. There are no significant discontinuities and > maximum excursions are in the 15 ms range. For a USB only device with no > PPS, I think this is a pretty good chart. It seems to me, this is > performing better. I'll admit I have to do more testing to confirm any > patterns. Please post again when you feel you have enough data for a valid comparison. > Actually, I've diverted my attention to troubleshooting a worse problem. > Once I figure that out, I plan to get back to the priority issue. After > about 3 days of rock solid operation similar to the above chart, my GPS > suddenly goes phycho on me. Offsets go wild and get up into the 100 ms > range. See the next file: > > http://dl.dropbox.com/u/9879631/loopstats.20120203p08-1-above-crazy-gps > > As you can see, this continued for about 12 hours until I got tired of it. > I stopped the ntpd service. Unplugged the GPS. Waited 30 seconds. Then > plugged it in again and restarted the ntpd service. Now I'm back to a > little over a full day of rock solid operation again. I'm waiting to see if > it freaks out 2 days from now. If anyone can help me determine what's up > with that, I'd be very grateful. I have verified that the TWO sets of > firmware in the device (one for GlobalSat and one for the SIRF III chipset) > are up to date as well as the USB - serial driver in my PC. I suspect a > design flaw in the GPS firmware, perhaps a memory leak, or maybe a similar > flaw in the Prolific USB - serial driver. However, I'm just speculating. That's a bizarre loopstats alright. In two 8 second intervals you go from < 5 msec offset to 80 msec and back to less than 5 msec, suggesting a wayward system clock. I wish I had more feedback -- this is unfamiliar territory for me, though A Carver's recent post regarding ntpd on netbsd/sparc had similarly wild loopstats, I don't really have any clue what might be causing either problem. > Here's my ntp.conf file: > > http://dl.dropbox.com/u/9879631/ntp.conf > > By the way, can you do attachments on this NTP Questions list. I think I > read somewhere that you cannot, which is why I'm using dropbox. However, I > may have to delete these files after a while.. Attachments and HTML are stripped by the mailing list. If space and/or clutter are a concern, you might consider using a pastebin website. Those often permit indefinite-lifetime posts (good until the site goes away or has trouble). Cheers, Dave Hart _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
