[erlang-questions] FreeBSD cpu topology detection

Garret Smith garret.smith@REDACTED
Sat Oct 18 05:58:07 CEST 2014

On Fri, Oct 17, 2014 at 9:34 AM, Garret Smith <garret.smith@REDACTED> wrote:
> On Thu, Oct 16, 2014 at 6:04 PM, Garret Smith <garret.smith@REDACTED> wrote:
>> CPU topology detection seems broken (at least incomplete) on FreeBSD.
>> erlang:system_info(cpu_topology) returns 'undefined' on the few machines I
>> have at my disposal.
>> I'm going to take a stab at a patch, but I'd like some help from other
>> FreeBSD users out there first.
>> Can any FreeBSD users please send me:
>>     a) the output of 'sysctl kern.sched.topology_spec'
>>     b) a few lines from your 'dmesg' about the processor configuration like:
>> FreeBSD/SMP: Multiprocessor System Detected: 8 CPUs
>> FreeBSD/SMP: 1 package(s) x 4 core(s) x 2 SMT threads
>> Even if your topology is correctly determined, this info will help me ensure
>> I don't introduce a regression.
>> Thanks,
>> Garret
> Thank you to all who sent me information.
> I now have a good collection of systems with {2, 4, 8} logical
> processors and {2, 4} cores.  Any info on machines with >8 logical
> processors would be appreciated.
> No one reported that topology detection worked.
> -Garret

First cut is up at:
I get the correct topology for my machine and the XML samples I was sent.

Any additional testing before I submit to the OTP team next week would
be appreciated.  I don't think they have a lot of boxen to really
exercise this.


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