[ntp:questions] Use ntpd as a daemon so that it continuously disciplines clock, no

River Tarnell r.tarnell at IEEE.ORG
Mon Jan 17 15:19:33 UTC 2011


In article <vs2dnZBjt4QHxanQnZ2dnUVZ_jydnZ2d at giganews.com>,
Richard B. Gilbert <rgilbert88 at comcast.net> wrote:
>On 1/17/2011 6:20 AM, Miroslav Lichvar wrote:
>> Even when completely idle, ntpd wakes up every second and does quite a
>> lot (updating timers, scanning the peer hash table, etc). I'd say that
>> starting ntpd two times per day will take much less resources than
>> running it continuosly.

>So running NTPD continuously eats 0.05% of the CPU!  Do you *really* care?

 3:13PM  up 26 days,  7:36, 1 user, load averages: 0.06, 0.09, 0.04

USER       PID %CPU %MEM    VSZ   RSS TTY    STAT STARTED      TIME COMMAND
root       255  0.0  1.8  24620 18744 ?      Ss   22Dec10  86:19.57 /usr/sbin/ntpd 

ntpd has been running 26 days (37890 minutes) and has used 86 minutes of CPU; 
i.e., 0.2% of a 2.3GHz Intel Core 2 CPU.  This is on a pool.ntp.org server that 
receives up to 100 queries/second.  CPU use on a less busy system would likely 
be a lot less.

I think it's fair to say that unless your CPU is *really* slow (embedded 
system?), ntp's CPU use is not worth worrying about -- especially given the 
advantages (more accurate time, even when the ntp server is unreachable).

	- river.




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