git: a8004081b8 - main - 2023q2 status: add MAXCPU report

From: Ed Maste <emaste_at_FreeBSD.org>
Date: Fri, 21 Jul 2023 20:22:36 UTC
The branch main has been updated by emaste:

URL: https://cgit.FreeBSD.org/doc/commit/?id=a8004081b8ec9d3e929c38683290c1fbadd40c27

commit a8004081b8ec9d3e929c38683290c1fbadd40c27
Author:     Ed Maste <emaste@FreeBSD.org>
AuthorDate: 2023-07-18 20:09:47 +0000
Commit:     Ed Maste <emaste@FreeBSD.org>
CommitDate: 2023-07-21 20:22:15 +0000

    2023q2 status: add MAXCPU report
    
    Reviewed by:    salvadore
    Sponsored by:   The FreeBSD Foundation
    Differential Revision: https://reviews.freebsd.org/D41142
---
 .../en/status/report-2023-04-2023-06/maxcpu.adoc       | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/website/content/en/status/report-2023-04-2023-06/maxcpu.adoc b/website/content/en/status/report-2023-04-2023-06/maxcpu.adoc
new file mode 100644
index 0000000000..3c0485946c
--- /dev/null
+++ b/website/content/en/status/report-2023-04-2023-06/maxcpu.adoc
@@ -0,0 +1,18 @@
+=== Increasing MAXCPU
+
+Links: +
+link:https://reviews.freebsd.org/D36838[Review D36838: amd64: Bump MAXCPU to 1024 (from 256)] URL: https://reviews.freebsd.org/D36838[]
+
+Contact: Ed Maste <emaste@FreeBSD.org>
+
+The default amd64 and arm64 FreeBSD kernel configurations currently support a maximum of 256 CPUs.
+A custom kernel can be built with support for larger core counts by setting the `MAXCPU` kernel option.
+However, commodity systems with more than 256 CPUs are becoming available and will be increasingly common during FreeBSD 14's support lifecycle.
+We want to increase the default maximum CPU count to 1024 to support these systems "out of the box" on FreeBSD 14.
+
+A number of changes have been made to support a larger default `MAXCPU`, including fixing the userland maximum for `cpuset_t` at 1024.
+Changes have also been made to avoid static `MAXCPU`-sized arrays, replacing them with on-demand memory allocation.
+
+Additional work is required to continue reducing static allocations sized by `MAXCPU` and addressing scalability bottlenecks on very high core count systems, but the goal is to release FreeBSD 14 with a stable ABI and KBI with support for large CPU counts.
+
+Sponsor: The FreeBSD Foundation