[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 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
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