find_acpi_cp...logy_cluster(9)

💅 find_acpi_cp...logy_cluster(9) — Kernel API Manual ✨

okay bestie, so this one lives in the Kernel API Manual and it's called find_acpi_cpu_topology_cluster — say that five times fast, i literally dare you 🫶

---

✨ NAME ✨

find_acpi_cpu_topology_cluster — determine a unique CPU cluster value 👑

---

🎀 SYNOPSIS 🎀

int find_acpi_cpu_topology_cluster (unsigned int cpu );

---

🌸 ARGUMENTS 🌸

• cpu — the kernel logical CPU number, bestie. that's the whole argument. she's low maintenance 💅

---

🦋 DESCRIPTION 🦋

okay so what this does is figure out a topology-unique cluster ID for whatever CPU/thread you hand it. and once you have that ID? you can group peers together — every peer with a matching ID is in the same little squad 💖

now for the lore: the cluster, if it's present, is the level of topology above CPUs. in a multi-thread CPU it's gonna be the level above the CPU, not the thread — important distinction, don't mix them up 🙈 it may not exist at all in single CPU systems, and in simple multi-CPU systems it may be equal to the package topology level. so like, sometimes the cluster vibe check and the package vibe check give you the same answer. no cap 🧚

---

🔥 RETURN 🔥

so here's the tea 😭 it returns -ENOENT if:

• the PPTT doesn't exist
• it can't get the CPU's ACPI Processor UID
• the CPU cannot be found
• or there is no topology level above the CPU

otherwise? it returns a value which represents the package for this CPU. slay 🎀

---

🌈 SEE ALSO 🌈

this is the group chat, and everyone's here 💜 kernel file ./drivers/acpi/pptt.c, plus:

acpi_pptt_walk_cache(9), acpi_count_levels(9), acpi_pptt_leaf_node(9), acpi_find_processor_node(9), update_cache_properties(9), topology_get_acpi_cpu_tag(9), check_acpi_cpu_flag(9), acpi_get_cache_info(9), cache_setup_acpi(9), acpi_pptt_cpu_is_thread(9), find_acpi_cpu_topology(9), find_acpi_cpu_topology_package(9), find_acpi_cpu_topology_hetero_id(9), acpi_pptt_get_child_cpus(9), acpi_pptt_get_cpus_from_container(9), find_acpi_cache_level_from_id(9), acpi_pptt_get_cpumask_from_cache_id(9)

---

ngl that's a lot of siblings but every single one of them ate, periodt 💀

---

and that's the whole page bestie, mwah 🫶 this icon dropped out of ./drivers/acpi and she's dated October 2026 ⭐ go read the source, ily, bye 💖