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View Full Version : [ubuntu] why does my system think I have a dual-core?



BetterSense
November 26th, 2008, 06:37 AM
I have an Acer Aspire One netbook. With intel Atom. Gnome's System Monitor, top, htop, and kpowersave all think I have two CPUs. Htop's CPU usage meters even individually move back and forth.

Hello? Did I get a preproduction dual-core Atom?

amauk
November 26th, 2008, 06:43 AM
Hyper-threading
http://en.wikipedia.org/wiki/Hyper-threading

Physically it's a single core CPU
but the OS "sees" a dual core because of the CPU hyper-threading

finito
November 26th, 2008, 09:44 AM
I have an Aspire one as well, I have windows installed and it also shows 2 processors.

BetterSense
November 26th, 2008, 08:44 PM
So if I had a quad-core, would ubuntu see all four cores or would it also say I had a dual-core?

My friend has kubuntu 8.04 and he says his system only shows one CPU.

dicecca112
November 26th, 2008, 08:53 PM
So if I had a quad-core, would ubuntu see all four cores or would it also say I had a dual-core?

My friend has kubuntu 8.04 and he says his system only shows one CPU.

4cores

amauk
November 26th, 2008, 09:01 PM
If you had a quad-core hyperthreaded Intel CPU (which don't exist as far as I'm aware, but just pretend) the OS would see eight cores

hyperthreading is hardware-based multi tasking implemented on certain intel CPU's (as opposed to the software scheduling done in the kernel)

physically, there's X cores
logically, there's 2X cores

if your friend has a single core, and the OS "sees" it as a single core, then it's not got hyperthreading

jespdj
November 26th, 2008, 09:04 PM
If you had a quad-core hyperthreaded Intel CPU (which don't exist as far as I'm aware, but just pretend) the OS would see eight cores
It does exist - the brand new Intel Core i7 processors have four cores and hyperthreading, so it will look like there are eight cores to the OS.

finito
November 26th, 2008, 11:35 PM
for the curious ones