redhat - CPUs - show double what is installed

[Jeff Hoevenaar]

I have a ProLiant DL580 G3 with 4 CPUs installed. But when I look at the /proc/cpuinfo it shows 8 CPUs installed. Also, when I run the "top" command it shows 8 CPUs.

Why is that?

[Steven E. Protter · Accepted solution]

Shalom Jeff,

Your CPU's have hyperthreading enabled. That is a virtual, software CPU, built into the hardware CPU. By default, it is enabled in the BIOS.

The OS see's the number of CPU's based on the virtual count.

4 hardware cpu's equal 8 top cpu's in this scenario.

Gets you 60% performance bump over older cpu's.

SEP

[Ivan Ferreira]

You have hyperthreading enabled, and you can see the real number of cpu by their physical ID. You will have two processors with the same physical ID.

[Vipulinux]

Hi

If the system has hyperthreading than it will show 1 CPU as 2
eg if ur system has 2 cpu it will show as 4.

In order to have alook at the real no. of CPU's do
cat /proc/cpuinfo

Cheers

[Jeff Hoevenaar]

thanks for the info!