Two Processors: Showing As Four?

[Kilo]

Hi all,

I've recently installed Fedora Core 1 on a Dell PowerEdge 1750, which has two Xeon 2.8GHz processors. I know there's two, I've counted them myself!

However, run top, and I see:
-----------------------------------------------------

10:01:36 up 1 day, 16:29, 1 user, load average: 1.00, 1.00, 1.00
64 processes: 63 sleeping, 1 running, 0 zombie, 0 stopped
CPU states: cpu user nice system irq softirq iowait idle
total 0.0% 0.0% 0.0% 0.4% 0.0% 0.0% 0.0%
cpu00 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%
cpu01 0.0% 0.0% 0.0% 0.1% 0.0% 0.0% 0.0%
cpu02 0.0% 0.0% 0.0% 0.0% 0.0% 0.1% 0.0%
cpu03 0.0% 0.0% 0.0% 0.0% 0.1% 0.0% 0.0%

---------------------------------------------------



I've got two questions; I've a feeling they're related:

(1) Why does it show four processors? I've installed Fedora Core 1 on a variety of other 1 and 2 processor machines and it's never got this wrong before.

I've a feeling this is due to "hyper threading". As long as it's normal, that's fine. BUT, this leads me to question 2.

(2) Having booted and allowed the machine to settle for a day(!), with no connections or applications running, the load settles at 1.00. Now on every other box I've ever come across, in the same circumstances, load settles at 0.00.

Is THIS normal?!

Any help and advice would be much appreciated.

[Varkk]

The four processor is the two hyper-threading CPUs being represented as 4 logical CPUs. (At least I think that is the way it works)

[i686]

Kilo:

basically Hyperthreading makes 1 physical cpu appear as 2 logical cpu's..

or 2 physical appear as 4 logical in your setup..

hyperthreading in most cases will improve performance of the computer..

i686

[Kilo]

Okay, thanks for the responses. But does this explain why my load settles out at 1.00 after a clean minimal install?

[Kilo]

Okay I've rebooted and switched off logical processory stuff(!) and it sees two CPUs, but the load still settles at 1.00. So I'll switch it back, close this and start a new thread about it all.

Ta.

[ewdi]

yes, HT CPU will show as 2 for each CPU.

Can you post your top -i stats when it hits load high?

[Kilo]

Hi tux,

I've started another thread on this, so to keep things tidy I've posted the "top -i" output there:

http://www.fedoraforum.org/forum/showthread.php?s=&postid=8946