Date: Wed, 18 Jun 2025 02:13:26 GMT From: Olivier Certner <olce@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: af8de65ef23e - main - runq: Switch to 256 levels Message-ID: <202506180213.55I2DQGW024508@gitrepo.freebsd.org>
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The branch main has been updated by olce: URL: https://cgit.FreeBSD.org/src/commit/?id=af8de65ef23e7e447916370851f39aea3f74e16a commit af8de65ef23e7e447916370851f39aea3f74e16a Author: Olivier Certner <olce@FreeBSD.org> AuthorDate: 2024-05-14 12:36:33 +0000 Commit: Olivier Certner <olce@FreeBSD.org> CommitDate: 2025-06-18 02:08:03 +0000 runq: Switch to 256 levels This increases the number of levels from 64 to 256, which coincides with the distinct internal priority values (priority is currently encoded in a 'u_char', whose range is entirely used). With this change, we become POSIX-compliant for SCHED_FIFO/SCHED_RR in that we really provide 32 distinct priority levels for these policies. Previously, threads in the same "priority group", with priority groups defined as the threads in consecutive spans of 4 priority levels starting with level 0 up to 31 (so there are 8 groups), could not preempt or be preempted by each other even if they were assigned different priority levels. See also commit "sched_ule: Use a single runqueue per CPU" for all the drawbacks that this change also removes. MFC after: 1 month Event: Kitchener-Waterloo Hackathon 202506 Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D45390 --- sys/sys/runq.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sys/sys/runq.h b/sys/sys/runq.h index 5f415740099f..590463af192c 100644 --- a/sys/sys/runq.h +++ b/sys/sys/runq.h @@ -42,7 +42,7 @@ */ #define RQ_MAX_PRIO (255) /* Maximum priority (minimum is 0). */ -#define RQ_PPQ (4) /* Priorities per queue. */ +#define RQ_PPQ (1) /* Priorities per queue. */ /* * Deduced from the above parameters and machine ones.
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