Kernel NTP flipping between FLL and PLL modes

[Jon Noack]

On 04/01/05 14:51, Vivek Khera wrote:
> On Apr 1, 2005, at 12:56 PM, Bob Bishop wrote:
>> At 18:42 01/04/2005, Roland Smith wrote:
>>> On my amd64 box I also get the mode flipping, but I don't get resets.
>>
>> Hmm. I am getting resets on my amd64.
> 
> On my dual opteron, I get flipping perhaps a handful of times per day 
> (5.4-PRE/amd64 from march 22).
> 
> On my Xeon EMT64 with hyperthreading (5.3-STABLE/amd64 from Jan 7), it 
> happens every 2-6 hours.
> 
> My 5.3-REL/i386 Xeon with hyperthreading does it about two or four times 
> per day, no resetting.
> 
> Neither one shows time step resets.

On my little LAN here I have one machine syncing with the Internet that 
acts as a time server for 3 others.  The time server machine (733MHz P3 
w/ 4BSD scheduler), named 'www', logs the following:
Apr  5 12:35:59 www ntpd[439]: ntpd 4.2.0-a Tue Apr  5 10:59:44 CDT 2005 (1)
Apr  5 12:44:33 www ntpd[439]: kernel time sync disabled 2041
Apr  5 12:53:07 www ntpd[439]: kernel time sync enabled 2001
Apr  5 17:36:27 www ntpd[439]: kernel time sync enabled 6001
Apr  5 17:53:31 www ntpd[439]: kernel time sync enabled 2001
Apr  5 18:44:43 www ntpd[439]: kernel time sync enabled 6001
Apr  5 19:01:46 www ntpd[439]: kernel time sync enabled 2001
Apr  5 20:44:12 www ntpd[439]: kernel time sync enabled 6001
Apr  5 21:01:16 www ntpd[439]: kernel time sync enabled 2001
Apr  6 00:26:11 www ntpd[439]: kernel time sync enabled 6001
Apr  6 00:43:16 www ntpd[439]: kernel time sync enabled 2001
Apr  6 02:25:43 www ntpd[439]: kernel time sync enabled 6001
Apr  6 02:42:46 www ntpd[439]: kernel time sync enabled 2001
Apr  6 05:33:31 www ntpd[439]: kernel time sync enabled 6001
Apr  6 05:50:37 www ntpd[439]: kernel time sync enabled 2001
Apr  6 07:50:09 www ntpd[439]: kernel time sync enabled 6001
Apr  6 08:07:14 www ntpd[439]: kernel time sync enabled 2001
Apr  6 09:15:31 www ntpd[439]: kernel time sync enabled 6001
Apr  6 09:32:37 www ntpd[439]: kernel time sync enabled 2001
Apr  6 11:32:07 www ntpd[439]: kernel time sync enabled 6001

2 of the clients (800MHz P3 and Althon XP 1800+, both w/ 4BSD scheduler) 
don't have any weird issues at all.  The third (4x 550MHz P3 Xeon w/ ULE 
scheduler), aptly named 'quad', hasn't flipped much but has a lot of resets:
Apr  5 12:45:28 quad ntpd[708]: ntpd 4.2.0-a Tue Apr  5 10:34:52 CDT 
2005 (1)
Apr  5 12:54:03 quad ntpd[708]: kernel time sync disabled 2041
Apr  5 13:05:48 quad ntpd[708]: kernel time sync enabled 2001
Apr  5 16:19:52 quad ntpd[708]: time reset -0.702001 s
Apr  5 17:05:57 quad ntpd[708]: time reset +1.232861 s
Apr  5 17:49:57 quad ntpd[708]: time reset -0.678139 s
Apr  5 19:01:45 quad ntpd[708]: time reset +0.183283 s
Apr  6 03:04:23 quad ntpd[708]: time reset -0.680651 s
Apr  6 03:27:53 quad ntpd[708]: time reset +0.158949 s
Apr  6 03:47:04 quad ntpd[708]: time reset +0.983025 s
Apr  6 04:24:39 quad ntpd[708]: time reset -1.101975 s
Apr  6 04:46:09 quad ntpd[708]: time reset +0.637136 s
Apr  6 11:51:31 quad ntpd[708]: kernel time sync enabled 6001
Apr  6 12:08:34 quad ntpd[708]: kernel time sync enabled 2001

Note that all machines are connected to the same 100Mbit switch and were 
rebooted at the same time.  I only got resets on the SMP/ULE machine. 
Perhaps SMP or ULE make the issue worse?

Jon