Re: How to determine Linux real CPUs vs hyperthreaded (ht) virtual CPUs?

From: Orak Listalavostok (oraklistal_at_yahoo.com)
Date: 05/31/04 

Date: 30 May 2004 21:09:46 -0700

> From: hzmonte (hzmonte@hotmail.com)
> Subject: how do I know hyperthreading is enabled
> Newsgroups: comp.os.linux.misc
> Date: 2004-03-15 04:56:54 PST
>
> how do I know hyperthreading is enabled on any arbitrary Linux PC?

a) This should report the total number of physical CPUs:
    grep -i "physical id" /proc/cpuinfo | sort -u | wc -l

b) This should report the total number of logical CPUs:
    grep -i "processor" /proc/cpuinfo | sort -u | wc -l

c) The difference, is hyperthreaded.

   Here is an annotated report from an IBM X335:
    egrep -i "processor|physical id" /proc/cpuinfo
    grep -E "processor|physical id" /proc/cpuinfo
   which outputs (for example):
      processor : 0 (CPU 0 is the first logical)
      physical id : 0 (CPU 0 is the first physical)
      processor : 1 (CPU 1 is the second logical)
      physical id : 3 (CPU 3 is the second physical)
      processor : 2 (CPU 2 is the third logical)
      physical id : 0 (CPU 0 is the first physical)
      processor : 3 (CPU 3 is the fourth logical)
      physical id : 3 (CPU 3 is the second physical)

Orak

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