Date: Wed, 17 Mar 2004 13:35:25 -0700 From: "Brent Wiese" <brently@bjwcs.com> To: <a@jenisch.at>, <freebsd-questions@freebsd.org> Subject: RE: SMP vs. Hyperthreading? Message-ID: <20040317203527.RVHD4381.fed1mtao07.cox.net@SAMBA> In-Reply-To: <20040313133737.GA21068@athena.oekb.co.at>
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> Hi,
>
> I've got a machine with a P4 that supports HTT (Hyperthreading) so I
> thought about setting up a SMP-kernel.
SMP <> HT. I'm not an expert on this, but when I went to an Intel conference
a couple years ago which discussed hyperthreading, it was made pretty clear
it wasn't the same as SMP. But, like I said, I'm not an expert so I don't
know what exactly its doing at the very low levels.
> Under 5.2.1 it's a different story though: /var/log/messages shows
> that there are 2 CPUs but the message indicating the second CPU has
> been launched is missing ("/kernel: SMP: AP CPU #1 Launched!"). When I
> run a "cpuburn"-Test under 5.2.1 CPU load indicated by "top" shows
> 100% so I assume SMP/HTT is not active.
That is the message for the second CPU. The first is CPU #0 and is always
active. Every dual-cpu machine I've installed SMP kernel on only shows the
second CPU launching.
> So my primary question is - how do I get SMP running under 5.2.1 with
> a hyperthreading-capable P4??
I haven't used 5.x, but in 4.9, there is a specific line in the kernel
config for hyperthreading support (to which I've read mixed reviews on this
list).
Good luck
Brent
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