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Date:      Tue, 10 Mar 1998 15:22:57 -0800
From:      Jamie Lawrence <jal@42is.com>
To:        questions@FreeBSD.ORG
Subject:   Load Averages: what exactly do they mean?
Message-ID:  <3.0.3.32.19980310152257.00a5b3c0@colonel.42inc.com>
In-Reply-To: <19980306164853.AAA27430@stimpy>

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Hi -

>From my reading of Design and Implementation of BSD4.4
my understanding of the load average calculation is that
it is the total of the number of processes ready to run or
waiting on IO divided by the total number of processes. This
implies that it should never go above 1. However, I've seen
it bounce above 1 before, and on other BSD variants, it does,
too:

xxxxxx:~> uname -a ; w | head -1
BSD/OS xxxxxx.xxxxxxxx.com 2.1 BSDI BSD/OS 2.1 Kernel #1: Sat May 25 18:58:46
PDT 1996     panic@xxxxx.xxxxxxxx.com:/usr/src/sys/compile/XANADU  i386
 6:38PM  up 115 days,  8:06, 5 users, load averages: 1.65, 1.55, 1.59

On Solaris boxes I manage, it regularly stays above 1 (in one test
situation where an Ultra 1 was being intentionally hammered, it
sat between 11 and 12 for hours), but I attributed this to System V
strangeness.

What exactly is the load average, and how is it calculated?

Thanks.

-j

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