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[perfsonar-user] Re: ultralight kernel and bwctl NTP: Status UNSYNC (clock offset problems likely)


Chronological Thread 
  • From: Lincoln Bryant <>
  • To: Shawn McKee <>
  • Cc: Hironori Ito <>, Jason Zurawski <>, Sarah Williams <>, perfsonar-user <>
  • Subject: [perfsonar-user] Re: ultralight kernel and bwctl NTP: Status UNSYNC (clock offset problems likely)
  • Date: Tue, 1 Apr 2014 13:46:39 -0500

I believe what is happening is that the kernel UNSYNC flag never gets cleared. 

[root@uct2-s19 ~]# /etc/init.d/ntpd restart
Shutting down ntpd:                                        [  OK  ]
ntpd: Synchronizing with time server:                      [  OK  ]
Syncing hardware clock to system time                      [  OK  ]
Starting ntpd:                                             [  OK  ]
[root@uct2-s19 ~]# ntpdc -c kerninfo
pll offset:           0 s
pll frequency:        0.000 ppm
maximum error:        0.001516 s
estimated error:      1.6e-05 s
status:               0040  unsync
pll time constant:    4
precision:            1e-06 s
frequency tolerance:  500 ppm

 1 Apr 13:45:51 ntpd[865015]: synchronized to 192.170.227.136, stratum 4

--Lincoln

On Apr 1, 2014, at 1:41 PM, Lincoln Bryant wrote:

I should add that our UL kernel is actually a derivative of the UltraLight kernel, rather than UltraLight 'proper'. Specifically, we are running kernel 3.2.13 for performance reasons.

I had some relevant information for this, let me see if I can dig it up. 

--Lincoln

On Apr 1, 2014, at 1:38 PM, Shawn McKee wrote:

Both  'bwctl'  and 'owping'  want  to  have  the  local  clock  correctly synchronized.

What  does  ntptime  show  on  this  host?

What  about  'ntpq -p' ?

What  is  in /etc/ntp.conf ?

Lincoln, Is  there  something  you hit  with  the  UltraLight  kernel that  is  messing  up ntp?

Thanks,

Shawn


On Tue, Apr 1, 2014 at 2:35 PM, Hironori Ito <> wrote:
Hello.

do you know how to get around the issue of the following error when bwctl is run?

[root@uct2-s20 ~]# bwctl -T nuttcp -c aofa-pt1.es.net -f m -i 2 -x -t 100
bwctl: NTP: Status UNSYNC (clock offset problems likely)
bwctl: NTP is unsynchronized. Skipping test. Use -a to run anyway.

Lincoln stats that it has something to do with ultralight kernel?

Hiro






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