From owner-freebsd-stable@FreeBSD.ORG  Wed Apr 25 11:50:38 2007
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Date: Wed, 25 Apr 2007 12:41:20 +0100
From: Richard Tector <richardtector@thekeelecentre.com>
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To: Artem Kuchin <matrix@itlegion.ru>
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Cc: freebsd-stable@freebsd.org
Subject: Re: Top not showing 4 cpus on  2 xeons with HT
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Artem Kuchin wrote:
> I am just wondering if it is normal.
> I have two xeon  processors with HT on each of them.
> When loading kernel says that 4 cpu's are found,
> but when i do top i can see only 0 or 2 in the C
> column. never 1 or 3. Is it normal?
>
> FreeBSD 6.2-STABLE (cvsed 1 day ago)
If I remember correctly, HT is disabled by default for security reasons 
but there should be a sysctl to enable it. I believe there is also a 
paper by Colin Percival on the issue.

Note that in a lot of common loads, the use of HT with the standard 
scheduler does not yield any real benefits.

Regards,

Richard