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

[matthew green <mrg%eterna23.net@localhost>]

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

From: matthew green <mrg%eterna23.net@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
    netbsd-bugs%netbsd.org@localhost, jtocino%gmx.com@localhost
Subject: re: kern/57816: Add sysctl support for physical cores
Date: Fri, 05 Jan 2024 16:18:01 +1100

 >  > It also has serious downsides:
 >  >  - it requires the user to be root
 >  >  - it requires one "cpuctl identify N" process for each cpu
 >  
 >  That's one of the design flaws of cpuctl. All data should be
 >  collected and provided by the kernel, including the information
 >  that cannot be collected from MSRs. That should make 'identify'
 >  a wrapper around sysctl.
 
 i wouldn't call it a design flaw of cpuctl, but of the x86
 backend for it :-)
 
 the arm and arm64 versions work via sysctl, and i think most
 of the sparc and sparc64 ones too.
 
 it wouldn't be bad to expose a lot of the basic things (eg,
 numa/package/core/smt IDs, maybe some more like base speed)
 in a MI tree like kern.cpu, most of the current ones are in
 machdep trees of course.
 
 
 .mrg.