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Re: Maximum logical cores / pfysical processors

I've CC-d you since it's not clear if you're familiar with Debian mailing list etiquette.

On Thu, 1 Aug 2013, Hayut, Eliott (EXP) wrote:
I was wondering if anybody could tell me the maximum number of logical cores and the maximum number of physical processors supported by Debian. I cannot seem to find this information online.

This depends on the hardware architecture and the particular kernel installed.

eg. on i386 with the -486 kernel:
$ grep NR_CPUS /boot/config-3.10-1-486

but that's deliberately a uniprocessor kernel..

whereas also on i386 with the (wheezy) -686-pae kernel:
$ grep NR_CPUS /boot/config-*

and on somewhat more modern hardware such as amd64 (also wheezy):
$ grep NR_CPUS /boot/config-*

which is enough for most people. nb. that number is a compile-time limit for how many hardware threads the Linux kernel will schedule tasks on. I don't believe there's any particular limits on packages or cores as long as your $PACKAGES * $CORES_PER_PACKAGE * $THREADS_PER_CORE <= NR_CPUS

On more exotic hardware you may wish to build your own kernel. Linux seems to support up to at least several thousand threads and there's no reason the rest of Debian shouldn't cope just fine.

Edward Allcutt

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