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ADJTIMEX
, man adjtimex :-)
, , -
" " (RTC - Real Time Clock), ,
, .
( 1 u), RTC, ,
(long-term stability). adjtimex
.
RTC
adjtimex --compare
, , (
RTC),
: tick .
,
RTC.
, RTC . clock(8)
hwclock(8) /etc/adjtime
(drift rate) RTC. adjtimex
RTC.
, adjtimex
(reference) , .
(drift rates).
"./configure", - "make",
"make install" /usr/local/bin,
man /usr/local/man/man8.
/usr /usr/local, "./configure --prefix=/usr".
root.
RTC,
(, adjtimex). , ,
ntpd , "" RTC
. adjtimex
. .
/etc/adjtime, clock(8) hwclock(8)
RTC. ,
man, . clock (
) (Rik Faith):
sunsite.unc.edu:pub/Linux/system/Misc/util-linux-1.10.tar.gz RTC
, /etc/adjtime,
: '0.0 0 0.0'.
.
adjtimex --compare.
:
# adjtimex --compare
794625929 -0.597638 -0.597638 ...
794625939 -0.602050 -0.004412 ...
^^^^^^^^^
, 4
10 RTC, 4 10000. ,
tick 10004 :
# adjtimex --tick 10004
# adjtimex --compare
794626037 -0.644860 -0.644860 ...
794626047 -0.645259 -0.000399 ...
39.9 .
(frequency offset).
, - ,
( 16 ). ,
39.9*65536 = 2614886:
# adjtimex --frequency 2614886
# adjtimex --compare
794626313 -0.652147 -0.652147 ...
794626323 -0.652247 -0.000100 ...
, 10 ppm,
10*65536, 3270246:
# adjtimex --frequency 3270246
# adjtimex --compare
794627233 -0.795221 -0.795221 ...
794627243 -0.795231 -0.000009 ...
"suggested" ("").
--adjust -
"" .
, --offset --singleshot
. tick
.
, , /etc/rc.d/rc.S, /etc/init.d/boot
:
# Adjust CMOS clock based on /etc/adjtime, then set system clock.
# Add -u switch if your system keeps GMT.
if [ -x /sbin/clock ]; then
/sbin/clock -a
fi
:
# Regulate the sytem clock
if [ -x /sbin/adjtimex ]; then
/sbin/adjtimex --tick 10004 --frequency 3270246
fi
adjtimex CMOS ,
(reference) ,
.
# adjtimex --log --watch
adjtimex , ,
.
.
, WWV CHU ..
ntpdate ( xntp)
,
# adjtimex --log --host www.xxx.yyy.zzz
adjtimex ntpdate
. ( , NTP,
.)
, log,
adjtimex
# adjtimex --review
(ppm) .
.
.
.
,
David L. Mills <mills@udel.edu>:
[MIL92a] Mills, D.L. Network Time Protocol (Version 3) specification,
implementation and analysis, RFC 1305, University of Delaware, March
1992, 113 pp.
[MIL92c] Mills, D.L. Simple Network Time Protocol (SNTP), RFC 1361,
University of Delaware, August 1992, 10 pp.
[MIL94a] Mills, D.L. A kernel model for precision timekeeping. ARPA
Network Working Group Report RFC-1589, University of Delaware, March
1994. 31 pp.
README.kern, louie.udel.edu:/pub/ntp/kernel.tar.Z.
(David Mills) ,
(Steven Dick) <ssd@nevets.oau.org>
adjtimex. ( . - .)
(Michael Meskes) <meskes@debian.org>,
Debian "--compare"
"--adjust".
!
- Jim Van Zandt <jrv at comcast.net>
|
