[675] in linux-net channel archive
Re: Getting and setting time for client, how?
daemon@ATHENA.MIT.EDU (Jonathan Stone)
Fri Jul 14 07:23:07 1995
To: Drew Eckhardt <drew@poohsticks.org>
cc: "linux-net (rutgers)" <linux-net@vger.rutgers.edu>,
Geis Jerry <GeisJ@rnd3.indy.tce.com>
Date: Thu, 13 Jul 1995 05:51:40 -0700
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
In message <199507120510.XAA00700@chopper.poohsticks.org>, Drew Eckhardt
<drew@poohsticks.org>, writes:
>In message <30016475@MSMAIL.INDY.TCE.COM>, GeisJ@rnd3.indy.tce.com writes:
>>
>>Hi all,
>> I am relatively new to networking and all and I'm wondering how to
>>once a day set the time of day on a client by asking a server? Whats the
>>best way to do this?
>I run xntpd on all my machines; you may wish to run it on one of your
>servers and run ntpdate out of a cron job on the other machines.
I can appreciate the simplicity of using only one synchronization
protocol on a network. Otherwise I don't see much point at all in
using xntpd (NTP is capable of long-term synchronization down to
microseconds) when one only has a 100hz-resolution interrupt-driven
clock, and one also lacks Dave Mills' phase-locked-loop clock
discipline, and the associated ntp_adjtime() call.
But, if you already have an NTP-disciplined clock nearby, use it!
>Another alternative is timed.
Yet another alternative is running xntpd on a ``master'' time server,
and using timed to distribute that master clock to clients. If you do
this, take care to ensure that, on the master server, only one daemon
is disciplining the clock. ``timed -F'' does this on BSD systems.
Is anyone working on high-resolution time for Linux -- e.g., with
microsecond, tens-of-nanosecond resolution or better? It's a great
way to tune networking (and other) code, widely available in Unix
workstation hardware; but I don't know of any widely-available
high-resolution free-running clock hardware for x86s. As far
as I know, motherboards don't include them, as a rule.
I'd appreciate any pointers to suitable hardware.
