Re: kern/57816: Add sysctl support for physical cores

[Martin Husemann <martin%duskware.de@localhost>]

The following reply was made to PR kern/57816; it has been noted by GNATS.

From: Martin Husemann <martin%duskware.de@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/57816: Add sysctl support for physical cores
Date: Thu, 4 Jan 2024 17:17:46 +0100

 On Thu, Jan 04, 2024 at 04:05:01PM +0000, Michael van Elst wrote:
 >  That information is currently available using the cpuctl identify command,
 >  but it's machine specific and probably delivers the information directly
 >  only for x86.
 
 It also has serious downsides:
  - it requires the user to be root
  - it requires one "cpuctl identify N" process for each cpu
 
 I'm also not sure it is all correct - I have a
 "AMD Ryzen 5 1400 Quad-Core Processor" with cpu0 ... cpu7, and e.g.
 
 cpu7: AMD Ryzen 5 1400 Quad-Core Processor           , id 0x800f11
 cpu7: node 0, package 0, core 5, smt 1
 
 (with cores 0, 1, 4 and 5 showing up)
 
 but "cpuctl identify 7" says:
 
 cpu7: Initial APIC ID 11
 cpu7: Cluster/Package ID 0
 cpu7: Core ID 1
 cpu7: SMT ID 1
 
 Martin