RE: SMP vs. Hyperthreading?
> 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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Re: SMP vs. Hyperthreading?
On Sat, Mar 13, 2004 at 02:37:37PM +0100, [EMAIL PROTECTED] wrote:
> Hi,
>
> I've got a machine with a P4 that supports HTT (Hyperthreading) so I
> thought about setting up a SMP-kernel.
>
> Under 4.9 it seems to work (see excerpts from /var/log/messages
> below), whereas on the same exact hardware under 5.2.1 I don't see two
> virtual CPUs working.
>
> For a first check I've run "cpuburn" (i.e. burnP6). Under 4.9 with one
> "cpuburn" process active "top" etc. show a cpu-load of about 50% which
> for me means SMP/HTT is active.
>
> 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.
>
>
> So my primary question is - how do I get SMP running under 5.2.1 with
> a hyperthreading-capable P4??
I installed 5.2 and that came ready to run afther the install. I didn't
have to do anything for it.
--
Alex
Articles based on solutions that I use:
http://www.kruijff.org/alex/index.php?dir=docs/FreeBSD/
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