Date: Wed, 18 Feb 2026 09:41:08 +0000 From: ShengYi Hung <aokblast@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: e387d9438ba0 - main - smp: Use bitwise operation to count cpu number Message-ID: <69958934.21605.2d0ec77a@gitrepo.freebsd.org>
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The branch main has been updated by aokblast: URL: https://cgit.FreeBSD.org/src/commit/?id=e387d9438ba0258b88ebe03ef139bc6fd70b5a46 commit e387d9438ba0258b88ebe03ef139bc6fd70b5a46 Author: ShengYi Hung <aokblast@FreeBSD.org> AuthorDate: 2026-01-03 16:32:50 +0000 Commit: ShengYi Hung <aokblast@FreeBSD.org> CommitDate: 2026-02-18 09:40:54 +0000 smp: Use bitwise operation to count cpu number Previously, we iterated over all CPUs using CPU_FOREACH and checked individual bits to count valid CPUs. Refactor this to use a bitwise AND and popcount to count the number of enabled bits directly. Approved by: markj (mentor) MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D54474 --- sys/kern/subr_smp.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/sys/kern/subr_smp.c b/sys/kern/subr_smp.c index 2256ba648e4d..148b366e7435 100644 --- a/sys/kern/subr_smp.c +++ b/sys/kern/subr_smp.c @@ -588,7 +588,7 @@ smp_rendezvous_cpus(cpuset_t map, void (* teardown_func)(void *), void *arg) { - int curcpumap, i, ncpus = 0; + int curcpumap, ncpus = 0; /* See comments in the !SMP case. */ if (!smp_started) { @@ -609,10 +609,8 @@ smp_rendezvous_cpus(cpuset_t map, */ MPASS(curthread->td_md.md_spinlock_count == 0); - CPU_FOREACH(i) { - if (CPU_ISSET(i, &map)) - ncpus++; - } + CPU_AND(&map, &map, &all_cpus); + ncpus = CPU_COUNT(&map); if (ncpus == 0) panic("ncpus is 0 with non-zero map");home | help
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