Re: NTP dumps Linux, film at 11. [Fwd/FYI]

Brandon S. Allbery KF8NH (
Tue, 01 Dec 1998 20:31:10 -0500

In message <199812020115.UAA29332@dcl.MIT.EDU>, "Theodore Y. Ts'o" writes:
| Date: Tue, 01 Dec 1998 18:03:07 -0500
| From: "Brandon S. Allbery KF8NH" <>
| The other thing about it is that it's not just lost interrupts: the
| systems are as apt to *gain* time, instead of losing it, again enough
| to make Kerberos upset (I've seen them gain 10 minutes over 5 minutes
| of wall time). Again, I haven't been able to correlate gain vs. loss
| (or amount thereof) to any particular program or device/driver.
| Hmm... I've never seen this myself. I've only lost time, on my clock,
| and only under very explainable circumstances (such as using the
| Bustoaster SCSI card). And I use Kerberos all the time, so I tend to

It was very noticeable. I upgraded the entire cluster (14 machines) in
HH1202 one afternoon; half the machines started gaining time like mad, the
other half lost time like mad. All machines identical, indeed from the same
manufacturing batch as far as I can tell (and all idle, the spring semester
having just ended at the time). Within 15 minutes all of them were outside
of the time window the AFS kaservers were willing to grant them (the usual 5
minutes for Kerberos) and linux-afs had lost the battle to resync their
clocks. (10 minutes later xntpd was a standard part of our Linux

Later in the summer I upgraded them all to RH5.1, with xntpd disabled
initially so I could see how they would behave. They proceeded to do much
the same thing, except that a few of them waited most of a week before
suddenly beginning to drift wildly.

Every (RH5-based) Linux system I've encountered, whether installed by me or
by someone else, has behaved similarly, although not always with such a
massive time slew (it varies widely and for no discernable reason, even on
the same machine).

I've only installed 5.2 on a handful of machines so far, but the time
slippages are still there so far.

brandon s. allbery	[os/2][linux][solaris][japh]
system administrator	     [WAY too many hats]
carnegie mellon / electrical and computer engineering			 KF8NH
			  Kiss my bits, Billy-boy.

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