Question on /proc/cpuinfo

Linux and Unix-Like Red Hat
1

Hi,

I wanted to understand what exactly /proc/cpuinfo shows?

We have a machine with following specification...

(2x) Intel Xeon 6-core processors

So, ideally it shouls have 12processors, but the output on /proc/cpuinfo shows 24 processors.

Can someone please explain how this is calculated.

Thanks!

2

This is likely due to hyper-threading. Each core supports two threads reported as separate virtual CPUs.

1 Like
3

Thanks jlliagre,

That answered the question, one more question, does hyperthread supports always 2 virtual cpu's / core? or it can vary... if yes, where can we see multiplying factor (2 in this case).

4

Hyperthreading, currently, is for 2 threads per core, however they share resources, and can cause some issues with performance. You may want to look output of using cat on /proc/cpuinfo and look for:

core id, cpu cores, physical id, siblings, and if you see the "word" ht in flags.

You can disable Hyperthreading. Since the two threads share resources, they are not deterministic in performance.