[ubuntu-uk] Do I have a quad-core netbook (surely not?!)

[Rob Beard]

On 28/06/11 13:21, Ross Mounce wrote:
> Dear list,
>
> I recently bought a fairly new Samsung N150 Plus netbook off a friend.
> Dumped the windows crippleware 'Starter' OS, and installed Ubuntu 64-bit
> 11.04

<snip>

>
> Two questions: A) Why does it show as 4 processors? Are these all real?

It uses a technology called Hyperthreading, it used to be used on the 
old Pentium 4 chips and Intel have started using it on the Atom and the 
new Core i5 and i7 CPUs.  Basically it makes the OS think that it has 
twice as many cores as it really has.

I understand that on applications that don't use the CPU much it can 
improve things but if you are running suff that hammers the CPU then 
there isn't much benefit.

I'd guess that if you're doing web browsing and what not then it might 
make things a little bit quicker, but it certainly isn't as quick as a 
real quad core CPU.

> Have I somehow 'unlocked' another couple *hopes*?

Nope, not on the Atom.  I've heard stories of the Athlon II and Phenom 
II chips being able to have cores 'unlocked' with certain motherboards 
and bioses as the X3 CPUs (and I believe Phenom X2 CPUs) tend to be X4 
CPUs that have had cores disabled.  Although I also gather that the 
cores may be disabled because of some faults, maybe such as they can't 
run at the rated speed or something.

>                         B) If it's just 4 threads, can I optimally run 4
> separate instances of a 32-bit program one each on each thread/core
> without losing overall efficiency? (The program I have in mind is a bit
> technical/obscure, and no, it doesn't have a 64-bit version)

Being a Hyperthreading CPU, I'd say yes and no.  Depends how much it 
uses the CPU.  It's been a while since I looked into Hyperthreading, 
this article on Wikipedia covers it better than I can explain it:

http://en.wikipedia.org/wiki/Hyper-threading

Rob