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To: Bruce Cran <bruce@cran.org.uk>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Tue, 06 Sep 2011 18:12:29 +0100."
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Date: Tue, 06 Sep 2011 17:22:02 +0000
Message-ID: <74959.1315329722@critter.freebsd.dk>
Cc: Garrett Cooper <yanegomi@gmail.com>, freebsd-current@freebsd.org,
	Alex Kozlov <spam@rm-rf.kiev.ua>
Subject: Re: Unusually high LA without any load at FreeBSD9-BETA2
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In message <4E66547D.2030907@cran.org.uk>, Bruce Cran writes:
>On 06/09/2011 18:05, Garrett Cooper wrote:
>> What is "LA"?
>
>Load Average?

We should kille the load avarage as a measure for system activity,
it only has any relevance if you run heavy CPU bound processes.

If the majority of your threads yield their quantum, load average
contains absolutely no information of any relevance to system
capacity.

Try this:

	main()
		for (i = 0; i < 10000; i++)
			start thread {
				calculate time until top of next second
				sleep (until then)
			}

You'll see a monster load-avg on idle cpus.


-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.