scx_cmask_ref_from_cpumask(9)

💖 scx_cmask_ref_from_cpumask(9) 💖

okay bestie, welcome to the Kernel API Manual page for scx_cmask_ref_from_cpumask(9) — yes, that whole mouthful. it's giving kernel API internals but make it cute ✨ and we're gonna get through it together, no cap.

🌸 NAME 🌸

scx_cmask_ref_from_cpumask — Populate @ref's arena cmask from a cpumask 💅

🎀 SYNOPSIS 🎀

void scx_cmask_ref_from_cpumask (const struct scx_cmask_ref *ref , const
       struct cpumask *cpumask );

🦋 ARGUMENTS 🦋

• ref — a kern-bound ref, see scx_cmask_ref_init_kern 🫶
• cpumask — cpus to translate into cids ⭐

🔥 DESCRIPTION 🔥

okay so here's the vibe: this function writes ref's active range one word at a time, and it sets each cid's bit when its cpu is in cpumask. 💖

the offsets and length come from ref's trusted geometry, and the stores use WRITE_ONCE because BPF may read concurrently — so the arena header is never read. periodt. 🧚

👑 SEE ALSO 👑

Kernel file ./kernel/sched/ext/cid.c — and these besties right here:

• scx_cid_publish_tables(9)
• scx_cid_retire_tables(9)
• scx_cid_init(9)
• scx_cmask_clear(9)
• scx_cmask_fill(9)
• scx_bpf_cid_override(9)
• scx_bpf_cid_to_cpu(9)
• scx_bpf_cpu_to_cid(9)
• scx_cmask_subset(9)
• scx_cmask_empty(9)
• scx_bpf_cid_topo(9)
• scx_cmask_ref_init(9)
• scx_cmask_ref_init_kern(9)
• scx_cmask_ref_shard(9)
• scx_cmask_ref_or(9)
• scx_cmask_ref_copy(9)

xoxo bestie 💖 — source/version: ./kernel/sched/ext, date: October 2026, page: scx_cmask_ref_from_cpumask(9).