[ntp:questions] Re: ntpd, boot time, and hot plugging

Tom Smith smith at cag.lkg.hp.com
Fri Feb 4 04:21:19 UTC 2005


Steve Kostecke wrote:
> 'ntpd -gq' blocks just like ntpdate. Try it and you'll see. The
> difference is that ntpd does a bit more work before it sets the clock
> and 'ntpd -gq' can use NTP authentication.

You're absolutely right. My mistake.

>>It would certainly be possible for ntpd to do this all by itself,
> 
> 
> It is.
> 

Yes, I wasn't clear. I meant that a single invocation of
ntpd could do this all by itself, as suggested by Brad.

The remaining issue, then, is that of the time required.

On a system already within less than a millisecond of nearly
all of its servers:

# time ntpd -gq [13 servers in ntp.conf]
ntpd: time slew -0.000373s

real    1m43.03s
user    0m0.10s
sys     0m0.60s

# time ntpdate -b [three selected servers]
  3 Feb 22:44:45 ntpdate[186032]: step time server [IP address] offset -0.000157 sec

real    0m0.90s
user    0m0.00s
sys     0m0.00s

I'm sure the time would be less with ntpd with fewer servers,
provided that all of them were up at boot time.

-Tom
________________________________________________________________________
Tom Smith                       smith at alum.mit.edu,smith at cag.lkg.hp.com
Hewlett-Packard Company                          Tel: +1 (603) 884-6329
110 Spit Brook Road ZKO1-3/H42                   FAX: +1 (603) 884-6484
Nashua, New Hampshire 03062-2698, USA           Mobile: +1 978 397 3411



More information about the questions mailing list