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Date:      Mon, 02 Jul 2007 12:51:23 -0400
From:      Chuck Swiger <cswiger@mac.com>
To:        Jack Stone <antennex@hotmail.com>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: kern.hz="100" stops high-pitched whine
Message-ID:  <46892D0B.3030205@mac.com>
In-Reply-To: <BAY125-F3001869A4CBB8CAF4B378BCC0D0@phx.gbl>
References:  <BAY125-F3001869A4CBB8CAF4B378BCC0D0@phx.gbl>

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Jack Stone wrote:
[ ... ]
> A while ago, I noticed someone's kernel config that included:
> hertz=2000 which made me wonder where this setting info comes from?
> 
> I've been using hertz=1000 however, with my much faster boxes, is this 
> appropriate now?

It depends on what you are doing: it is most useful to tune HZ higher when 
machines are being used as firewalls/routers and/or are using device polling. 
  Faster HZ rates cause greater system overhead but will give shorter latency, 
up to a limiting point.

In simpler words, tuning HZ too high is bad.  :-)
One needs to do measurements and tune appropriately.

-- 
-Chuck



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