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Date:      Fri, 8 Sep 2000 06:54:52 +1000 (EST)
From:      Ian Smith <smithi@nimnet.asn.au>
To:        Vivek Khera <khera@kciLink.com>
Cc:        stable@FreeBSD.ORG
Subject:   Re: Odd Load average problem
Message-ID:  <Pine.BSF.3.96.1000908064743.20849C-100000@gaia.nimnet.asn.au>
In-Reply-To: <14775.65131.298732.839601@onceler.kciLink.com>

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On Thu, 7 Sep 2000, Vivek Khera wrote:

 > >>>>> "IS" == Ian Smith <smithi@nimnet.asn.au> writes:
 > 
 > IS> For what it's worth, I've noticed this occasionally over a couple of
 > IS> years on a 2.2.6 box; same, seems like 1.00 has been added to the load
 > IS> average, lasts for hours, goes away.  Thought it'd be fixed ages ago :)
 > 
 > There was a big discussion about this on the bsdi-users mailing list a
 > year or so ago.  The gist of the problem was that on x86 architecture,
 > you don't have enough timers to measure the system without affecting
 > the system.  Something about needing to make the resolution of the
 > measuring timer be relatively prime to the scheduling timer.  Thus, it
 > is possible for the two logical timers to get in sync and artifically
 > increase the load.  Usually running some CPU intensive job breaks the
 > synchronization.

Guess that makes some sort of sense.  Oddly maybe, I most often noticed
this after running top just after an /etc/daily /etc/security run, one
of the few times of day that the l.a. ever gets past 1 around here ..

 > This is from memory, so may be slightly inaccurate, and may not apply
 > to FreeBSD, though I suspect it does considering the issue was with
 > the hardware capabilities.

A mystery it remains.  Not one I've been too stressed about, but still.

Thanks, Ian



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