On Wed, Jun 30, 2010 at 10:00:06PM +0000, David L. Mills wrote: > The change in SHIFT_PLL would result > in unstable behavior below 5 (32 s), as well as serious transients > if the discipline shifts from the daemon to the kernel and back. All > feedback loops become unstable unless the time constant is at least > several times the frequency update interval, which is this case is > one second. If you do want to explore how stability may be affected, > restore the original design and recompile the distribution with > NTP_MINPOLL changed from 3 to 1.
I recompiled ntpd with NTP_MINPOLL 1 and here is a PLL response plot for SHIFT_PLL 4 poll 1 and SHIFT_PLL 2 poll 3: http://fedorapeople.org/~mlichvar/clknetsim/test6.png The initial offset is 0.1 second, after crossing zero offset, they both stay in negative. -- Miroslav Lichvar _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
