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Does 2 Quad core with hyper threading equal to how many processor in linux

 
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senthil_kumar_2
Regular Advisor

Does 2 Quad core with hyper threading equal to how many processor in linux

Hi All,

We have 2 Quad core processors with hyper threading enabled.

How many processors will be seen in /proc/cpuinfo of redhat and suse linux.
3 REPLIES
Nils_9
Advisor
Solution

Re: Does 2 Quad core with hyper threading equal to how many processor in linux

Hi,

1 HT-enabled Quad core processor shows 8 processors in Red Hat, so 2 should show 16 processors. Unless the kernel (for commercial reasons) has not been enabled to see them.

Don't forget to check in the BIOS if Hyper Threading is enabled.

I checked on a Intel Core i7 920 system : both Fedora 14 x86_64 and CentOS 5 x86_64 display 8 processors (from 0 to 7) in /proc/cpuinfo .

Hope this helps,

Nils
senthil_kumar_2
Regular Advisor

Re: Does 2 Quad core with hyper threading equal to how many processor in linux

Thanks a lot.
Zinky
Honored Contributor

Re: Does 2 Quad core with hyper threading equal to how many processor in linux

Senthil, it really "depends" on what processor you're on. INTEL, Power, IA64 and SPARC processors currently support CPU threading which may be dual threading for most or up to quad threads for Sparcs (CMT).

And yes, a hyperthread is counted as 1 CPU by the OS. So Nehalems and core i7,i5,i3 families from INTEL employ two hyperthreads per CPU core.

From a Licensing Standpoint -- be very careful though when furnishing your vendor with "CPU count". Ask them specifically what they want -- whether they license products by the CPU socket or CPU core. I've seen shops paying needlessly more thinking they've more CPU cores that than they really have with Hyperthreading on.

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