perfSONAR User Q&A and Other Discussion

[Lincoln Bryant <>]

[root@uct2-s19 ~]# ntpq -p

     remote           refid      st t when poll reach   delay   offset  jitter

==============================================================================

*uct2-grid9.mwt2 128.135.247.50   4 u    9   64   37    0.151    0.114   0.043

[root@uct2-s19 ~]# cat /etc/ntp.conf

server  uct2-grid9.mwt2.org burst iburst

restrict  uct2-grid9.mwt2.org mask 255.255.255.255 nomodify notrap

restrict default ignore

restrict 127.0.0.1

driftfile /var/lib/ntp/ntp.drift

logfile /var/log/ntp.log

On Apr 1, 2014, at 1:49 PM, Shawn McKee wrote:

HI  Lincoln,

What  does   'ntpq  -p'  show?     What  is  in  /etc/ntp.conf ?

Thanks,

Shawn

On Tue, Apr 1, 2014 at 2:46 PM, Lincoln Bryant <> wrote:

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