topic Does 2 Quad core with hyper threading equal to how many processor in linux in Operating System - Linux

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

senthil_kumar_2 — Thu, 23 Dec 2010 19:42:21 GMT

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.

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

Nils_9 — Thu, 23 Dec 2010 22:47:59 GMT

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

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

senthil_kumar_2 — Fri, 24 Dec 2010 16:13:49 GMT

Thanks a lot.

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

Zinky — Mon, 27 Dec 2010 14:18:26 GMT

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.