Re: smp: am i seeing double?
On Fri, 12 Nov 2004 17:14:28 -0000, linux
<linux@networkingnewsletter.org.uk> wrote:
> A quick question about hardware. I'm 99% sure my box has 2 Xeon processors in
> it. I had installed the sarge kernel then got the
> kernel-image-2.4.27-1-686-smp_2.4.27-1.backports.org.1_i386.deb
> package and installed smoothly using `dpkg -i <kernel-image... .deb>`, rebooted
> into that kernel. I now seem to be seeing 4 (four!) processors eg as reported by
> `top`, `cat /proc/cpulist` and in the /var/log/messages file. (Aside: with the
> uni-processor kernel, `top` only reported 1Gb memory but the smp kernel,
> correctly, reports the 2Gb memory
>
> I've just rebooted to WinXP and the SystemProperties implies there's 2
> processors on the 'General' tab, but lists 4 on the
> Hardware->DeviceManager->Processors tab and indeed the TaskManager also implies
> there's 4 CPUs.
>
> Any ideas what's going on?
It's because of hyperthreading. Each processor appears like two to the
OS. You can most likely change it in your BIOS if you think your OS
performs better with two CPU's instead of four (there are cases this
might be true).
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