On 2011-03-22, Chris Albertson <albertson.ch...@gmail.com> wrote: > On Mon, Mar 21, 2011 at 11:38 PM, prashant sherin <pvs...@yahoo.com> wrote: >> Hi, >> I would like to know if ntpd would use the driftfile specified in /etc/ >> ntp.conf file if it is run periodically using crontab with -q option >> as below: > > That is a rather resource intensive way to run NTP. You use fewer > CPU cycles just letting ntpd run in the background. ntpd will decide > all by itself that it can "sleep" once the clock is running well. > The longer ntp has been running the longer these sleep periods tend to > be. It actually does more work when it starts up than after running > for a few hours. Placing it in the cron tab will force NTP to > endlessly go through the hard work of staring up. > > You want a really bad car analogy? To bad you get one anyway.... > Cars use most of their gas accelerating up to speed after stopping for > a red light. They use the least gas when cruising at steady speed of > 35MPH. Same with NTP by far most of the resources are used in the > fist minute or so. First off Cron has to create a shell process and > that process creates an instances of NTP by loadingit's code from the > disk into RAM, ntp then exchanges messages with other ntp servers at a > relatively fast rate. but after ntpd has been running for a few hours > it has settled into doing almost nothing
The amount of work done by ntpd even when it is working hard ( on startup) is completely trivial. This is like worrying about how much the weight of your crisps packet contributes to the reduction in gas milage on your car, while driving a V8 1/2ton truck. The cost of ntpd is completely swamped by all kinds of other inefficiencies in your operating system. (Of course if you are on a bicycle in the tour de France, it may be a legitimate worry). _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
