Non-resident ntp?

For Developers
#1

Trying to optimize RAM usage on a 32MB device, I noticed, that ntp is permanently resident in RAM. Any suggestions how to replace it, i.e. using cron to do single-shot time syncs periodically ?

#2

Use the -n option to prevent ntpd becoming a daemon also -q option looks interesting.

# ntpd -h
ntpd: unrecognized option: h
BusyBox v1.28.4 () multi-call binary.

Usage: ntpd [-dnqNwl -I IFACE] [-S PROG] [-p PEER]...

NTP client/server

        -d      Verbose (may be repeated)
        -n      Do not daemonize
        -q      Quit after clock is set
        -N      Run at high priority
        -w      Do not set time (only query peers), implies -n
        -S PROG Run PROG after stepping time, stratum change, and every 11 mins
        -p PEER Obtain time from PEER (may be repeated)
        -l      Also run as server on port 123
        -I IFACE Bind server to IFACE, implies -l
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#3

Depending on how accurate you need your notion of time, 802.11 requires 25 ppm accuracy for 2.4 GHz and 20 ppm accuracy for 5 GHz.

25 ppm over an hour, for reference, is 90 ms per hour, or a little over 2 seconds a day. (This assumes the kernel clock is based off the same crystal as used for the radios' frequency sysnthesis.)

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