Re: Disabling CPUs

 (Resending with list included)

Hey Keith,

Taken from smp(4):

     FreeBSD allows specific CPUs on a multi-processor system to be
disabled.
     This can be done using the hint.lapic.X.disabled tunable, where X is
the
     APIC ID of a CPU.  Setting this tunable to 1 will result in the
     corresponding CPU being disabled.

smp(4) further describes how to detect CPU topologies and whatnot.
Specifically the following sysctl seems useful: kern.sched.topology_spec

Though I'm not entirely sure, I'd personally start with the above.

~Paul

On Wed, Sep 21, 2022 at 10:06 PM Kevin Oberman <rkoberman@gmail.com> wrote:

> I am looking to disable all 8 E-cores on my Alder Lake system to prevent
> repeated crashes. The man page has an example of this:
> Modify the cpuset all threads are in by default to contain only the first
> 4 CPUs, leaving the rest idle:
>            cpuset -l 0-3 -s 1
> I did this, but in subsequent port build, all 12 "CPUs" were running at
> 100%. Am I missing something? Maybe use -p 1" instead of "-s 1".
>
> I also found suggestions to use "hint.lapic.N.disabled", but teh lines
> that were supposed to be in dmesg and the messages log were not present. I
> am baffled, but really need to do something to stop the crashes currently
> impacting Alder Lake systems.
> --
> Kevin Oberman, Part time kid herder and retired Network Engineer
> E-mail: rkoberman@gmail.com
> PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683
>


-- 
__________________

:(){ :|:& };: