scx_cid_init(9)

🌸 scx_cid_init(9) — Kernel API Manual, bestie 🌸

✨ NAME ✨

scx_cid_init — build the cid mapping. That's it, that's the whole name section, and it ate. 💅

💖 SYNOPSIS 💖

okay so the signature is literally:

s32 scx_cid_init (struct scx_sched *sch );

No cap, that's the exact line. 🫶

🌈 ARGUMENTS 🌈

• sch — the scx_sched being initialized; used as the scx_error target. Literally the target for errors, so be nice to it. 💜

🦋 DESCRIPTION 🦋

so like, this function builds a fresh table set. ✨ It becomes visible through scx_cid_publish_tables and is retired by scx_cid_retire_tables at disable. The vibes are: publish it, then retire it when disabled.

For the model, check "Topological CPU IDs" in cid.h — that's the lore, iykyk. 👑

The way it works: walk online cpus by intersection at each level (parent_scratch & this_level_mask), which keeps containment correct by construction and naturally splits a physical LLC straddling two NUMA nodes into two LLC units. highkey iconic behavior from the topology. 🌸

⚠️ The caller must hold cpus_read_lock. This is not a drill, bestie. 🔥

👑 SEE ALSO 👑

Kernel file: ./kernel/sched/ext/cid.c — the actual kernel file, go read it, it's giving source. 📖

• scx_cid_publish_tables(9)
• scx_cid_retire_tables(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)
• scx_cmask_ref_from_cpumask(9)

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xoxo, your kernel bestie 💖 — this page is from ./kernel/sched/ext, dated October 2026, and it's literally scx_cid_init(9). periodt. 🎀