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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Gabriel Paubert <paubert@iram.es>
Cc: linuxppc-dev list <linuxppc-dev@lists.linuxppc.org>,
	Linux Kernel list <linux-kernel@vger.kernel.org>
Subject: Re: Time precision, adjtime(x) vs. gettimeofday
Date: Wed, 08 Oct 2003 20:22:04 +0200	[thread overview]
Message-ID: <1065637323.897.12.camel@gaston> (raw)
In-Reply-To: <20031008175059.GA31743@iram.es>


> I repeat the question: what are the values of drift on the machines
> that encounter the problem ? Is this drift stable or unstable?

So far, there is no problem. The problem that was happening
was a via_calibrate_decr() bug with HZ != 100, but when
investigating, I figured out that we had a potential problem
there, that's all and that's why I want people like you who
know those problems well to state if it's worth bothering ;)
> >
> > On all cases, those will drift some way from what the NTP server will
> > give, either a lot or not, it will. So we may end up adjusting our
> > kernel rate and thus opening a window for the problem.
> 
> The worst variations of drift I've seen are a few ppm for a given
> machine, barring the occasional boot-time calibration problems that
> I have encountered.

OK.




  reply	other threads:[~2003-10-08 18:23 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-10-08 13:32 Time precision, adjtime(x) vs. gettimeofday Benjamin Herrenschmidt
2003-10-08 15:48 ` Gabriel Paubert
2003-10-08 16:22   ` Benjamin Herrenschmidt
2003-10-08 17:50     ` Gabriel Paubert
2003-10-08 18:22       ` Benjamin Herrenschmidt [this message]
2003-10-08 18:25 ` [PATCH] " Stephen Hemminger
2003-10-08 18:43   ` Benjamin Herrenschmidt
2003-10-08 19:11   ` john stultz
2003-10-08 22:17 ` Pavel Machek
2003-10-10  5:12 Bill Fink
2003-10-10  7:33 ` Gabriel Paubert
2003-10-10 16:39   ` Bill Fink
2003-10-10  7:53 ` Ethan Benson
2003-10-11  4:45 Bill Fink
2003-10-11  5:27 ` Ethan Benson
2003-10-11 14:58   ` Benjamin Herrenschmidt
2003-10-14  7:07     ` Gabriel Paubert
2003-10-14 11:16       ` Benjamin Herrenschmidt

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