Top not showing 4 cpus on 2 xeons with HT
tevans.uk at googlemail.com
Wed Apr 25 13:04:26 UTC 2007
On Wed, 2007-04-25 at 16:50 +0400, Artem Kuchin wrote:
> Richard Tector wrote:
> > 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.
> ahh, heck, i'll take my chances. I've read the paper and the attack
> seem to me almost unreal. Also, everybody is in the jail on the server.
> > Note that in a lot of common loads, the use of HT with the standard
> > scheduler does not yield any real benefits.
> Hmm. I just turned it on and already see that hosts are running generally
> faster (it is a hosting server, 100+ site). No numbers though. It just
> *SEEMS* faster. Anyway, it cannot make thing slower for sure, or
> can it?
> freebsd-stable at freebsd.org mailing list
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Yes, quite easily.
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