Re: [LEAPSECS] Improvements since 2012
Steve Allen writes: On Sat 2015-01-10T22:53:14 -0800, Ask Bj=F8rn Hansen hath writ: What's better about NTP and the NTP Pool since 2012? This is a question better answered by David Malone based on his long-term monitoring of the leap flags in the NTP pool, but ... At the end of 2012 July there were false leap second events from NTP pool servers which were inappropriately advertising that a leap was still pending. This happened again at the end of 2012 August. I don't know if those servers were upgraded to better versions of NTP or if they were simply excluded from the pool, but the false leap flags seem to be way down by now. This is almost certainly not a problem with NTP. It is almost certainly a problem with either a refclock (or a signal being fed to a refclock) or folks having bad leapsecond data, or manually forcing a leap second notice. -- Harlan Stenn st...@ntp.org http://networktimefoundation.org - be a member! ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Improvements since 2012
There were false leap second events six months ago. I didn't hear of any coinciding with the new year. See the brief thread starting at https://pairlist6.pair.net/pipermail/leapsecs/2014-July/005130.html Tony. -- f.anthony.n.finch d...@dotat.at http://dotat.at On 11 Jan 2015, at 21:17, Steve Allen s...@ucolick.org wrote: On Sat 2015-01-10T22:53:14 -0800, Ask Bjørn Hansen hath writ: What's better about NTP and the NTP Pool since 2012? This is a question better answered by David Malone based on his long-term monitoring of the leap flags in the NTP pool, but ... At the end of 2012 July there were false leap second events from NTP pool servers which were inappropriately advertising that a leap was still pending. This happened again at the end of 2012 August. I don't know if those servers were upgraded to better versions of NTP or if they were simply excluded from the pool, but the false leap flags seem to be way down by now. -- Steve Allen s...@ucolick.orgWGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165Lat +36.99855 1156 High StreetVoice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064http://www.ucolick.org/~sla/ Hgt +250 m ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] Improvements since 2012
Folks, originally I wrote this email about 9 hours ago, but sent it using a different email address which is not subscribed to the list. So apparingly the first email was blocked, and I'm sending it once more. Ask Bjørn Hansen wrote: Steve Allen s...@ucolick.org wrote: [...] NTP and the NTP pool are more robust too, so that will be better. What's better about NTP and the NTP Pool since 2012? I try not to mean that as a retorical question; I'm interested -- it would be good news. I don't know what's better about them and in the case of the pool I should probably know. :-) The main problem with the last leap seconds was due to implementation faults in the Linux kernel, when the leap second was handled. At the leap second in June 2012 this could cause a load spike (and thus increased power consumption). See: https://lkml.org/lkml/2012/7/1/27 At the leap second at the end of 2008 it was even worse and could cause a deadlock of the Linux kernel. See: https://lkml.org/lkml/2009/1/2/373 I don't know exactly from memory in which versions these bugs have been fixed, but I'll have a closer look at this the next days. If I remember correctly the Linux kernel maintainers have very carefully checked the leap second handling code, and provided some testing routines for it. So unless a new bug has been introduced I'd expect this works now in current kernel versions. In ntpd there has been a bug which could cause a leap second loop when a leap second warning was propagated in a loop and could cause another leap second warning for the end of the next month after a real leap second. If I remember correctly then this happened only under certain conditions, i.e. with certain configurations, and as far as I know there has been a patch in 4.2.8 which avoids this. Anyway, if the pool's NTP server monitoring software checks the leap second warning bit and detects a leap second warning is still lit after the leap second has already occurred you have 1 month time to fix this, which means you have just to restart ntpd on the affected machine. As always, this depends on the versions of the kernel and ntpd you are running. Martin ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
[LEAPSECS] Improvements since 2012
Steve Allen s...@ucolick.org wrote: [...] NTP and the NTP pool are more robust too, so that will be better. What's better about NTP and the NTP Pool since 2012? I try not to mean that as a retorical question; I'm interested -- it would be good news. I don't know what's better about them and in the case of the pool I should probably know. :-) Ask ___ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
