Date: Sat, 10 Jul 1999 01:49:26 -0600 From: Chris Fedde <cfedde@fedde.littleton.co.us> To: dg@root.com Cc: junkmale@xtra.co.nz, freebsd-questions@FreeBSD.ORG Subject: Re: Uptime basics!!! Message-ID: <199907100749.BAA98281@fedde.littleton.co.us> In-Reply-To: Your message of "Fri, 09 Jul 1999 01:38:05 PDT." <199907090838.BAA08058@implode.root.com>
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Digging into my bookshelf I find a definition of the load average
in _The Design and Implementation of the 4.3BSD UNIX Operating System_
in the section on Process Scheduling.
...where /load/ is a sampled average of the length of the run queue
over the previous 1 minute interval of system operation.
It is also defined in the glossary of the same book. Unfortunately
my copy of the 4.4 book is out on loan so I can't confirm that the
text is there too.
chris
David Greenman writes:
>On 8 Jul 99, at 19:41, David Greenman wrote:
>
>> Uh, no, that is not what the load average means. The load average is
a
>> composite number that includes both runnable processes and processes tha
t
>> are blocked in a short term wait (usually disk I/O). This means that for
>> machines that are doing heavy disk I/O, the load average could be quite
>> high even when the CPU is 95% idle. On wcarchive, for example, the load
>> average typically runs around 40-50 with 50% CPU idle time. This may sou
nd
>> high, but there are 38 disk drives on the machine, so although the drive
s
>> are fairly busy, the I/O is spread out over all of them - keeping the
>> interactive response time low and overall performance quite high.
>
>Where is this documented? I was trying to locate just this very
>information during the past week. Nothing in man uptime. If it belongs
>there, I volunteer to update it. How?
It should be documented in the man page for 'uptime' and 'w', but I see
that 'w' gets it wrong and 'uptime' doesn't say anything.
-DG
David Greenman
Co-founder/Principal Architect, The FreeBSD Project - http://www.freebsd.or
g
Creator of high-performance Internet servers - http://www.terasolutions.com
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Chris Fedde <cfedde@sendmail.com>
303 773 9134
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