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