precompute_cache_shard_ids(9)

💖 NAME 💖

okay so bestie, you're looking at precompute_cache_shard_ids(9) from the Kernel API Manual, section 9 ✨. Its whole mission? Assign each CPU its shard index within its LLC. That's it. That's the assignment. periodt. 💅

✨ SYNOPSIS ✨

void precompute_cache_shard_ids (void );

🫶 ARGUMENTS 🫶

• void — no arguments. literally zero. not even one tiny parameter. 💀

🌸 DESCRIPTION 🌸

Here's the whole plot, bestie: precompute_cache_shard_ids iterates over all LLC pods. For each pod, it counts distinct cores, then assigns shard indices to all CPUs in the pod. That's the vibe. 🦋

⚠️ Important caveat, no cap: it must be called after WQ_AFFN_CACHE and WQ_AFFN_SMT have been initialized. So do that first, okay? 💅

👑 SEE ALSO 👑

Kernel file ./kernel/workqueue.c — and the whole friend group is:

• for_each_pool(9)
• for_each_pool_worker(9)
• for_each_pwq(9)
• worker_pool_assign_id(9)
• unbound_effective_cpumask(9)
• get_work_pool(9)
• worker_set_flags(9)
• worker_clr_flags(9)
• worker_enter_idle(9)
• worker_leave_idle(9)
• find_worker_executing_work(9)
• move_linked_works(9)
• assign_work(9)
• kick_pool_pick(9)
• kick_pool(9)
• wq_worker_running(9)
• wq_worker_sleeping(9)
• wq_worker_tick(9)
• wq_worker_last_func(9)
• wq_node_nr_active(9)
• wq_update_node_max_active(9)
• get_pwq(9)
• put_pwq(9)
• put_pwq_unlocked(9)
• pwq_tryinc_nr_active(9)
• pwq_activate_first_inactive(9)
• unplug_oldest_pwq(9)
• node_activate_pending_pwq(9)
• pwq_dec_nr_active(9)
• pwq_dec_nr_in_flight(9)
• try_to_grab_pending(9)
• work_grab_pending(9)
• insert_work(9)
• queue_work_on(9)
• select_numa_node_cpu(9)
• queue_work_node(9)
• queue_delayed_work_on(9)
• mod_delayed_work_on(9)
• queue_rcu_work(9)
• worker_attach_to_pool(9)
• worker_detach_from_pool(9)
• create_worker(9)
• set_worker_dying(9)
• idle_worker_timeout(9)
• idle_cull_fn(9)
• maybe_create_worker(9)
• manage_workers(9)
• process_one_work(9)
• process_scheduled_works(9)
• worker_thread(9)
• rescuer_thread(9)
• check_flush_dependency(9)
• insert_wq_barrier(9)
• flush_workqueue_prep_pwqs(9)
• __flush_workqueue(9)
• drain_workqueue(9)
• flush_work(9)
• flush_delayed_work(9)
• flush_rcu_work(9)
• cancel_work_sync(9)
• cancel_delayed_work(9)
• cancel_delayed_work_sync(9)
• disable_work(9)
• disable_work_sync(9)
• enable_work(9)
• disable_delayed_work(9)
• disable_delayed_work_sync(9)
• enable_delayed_work(9)
• schedule_on_each_cpu(9)
• execute_in_process_context(9)
• free_workqueue_attrs(9)
• alloc_workqueue_attrs(9)
• init_worker_pool(9)
• put_unbound_pool(9)
• get_unbound_pool(9)
• wq_calc_pod_cpumask(9)
• apply_workqueue_attrs(9)
• unbound_wq_update_pwq(9)
• wq_adjust_max_active(9)
• destroy_workqueue(9)
• workqueue_set_max_active(9)
• workqueue_set_min_active(9)
• current_work(9)
• current_is_workqueue_rescuer(9)
• current_is_workqueue_mem_reclaim(9)
• workqueue_congested(9)
• work_busy(9)
• set_worker_desc(9)
• print_worker_info(9)
• show_one_workqueue(9)
• show_one_worker_pool(9)
• show_all_workqueues(9)
• show_freezable_workqueues(9)
• rebind_workers(9)
• restore_unbound_workers_cpumask(9)
• work_on_cpu_key(9)
• freeze_workqueues_begin(9)
• freeze_workqueues_busy(9)
• thaw_workqueues(9)
• workqueue_unbound_housekeeping_update(9)
• workqueue_set_unbound_cpumask(9)
• workqueue_sysfs_register(9)
• workqueue_sysfs_unregister(9)
• workqueue_init_early(9)
• workqueue_init(9)
• llc_count_cores(9)
• llc_populate_cpu_shard_id(9)
• workqueue_init_topology(9)

xoxo, from ./kernel • dated October 2026 • precompute_cache_shard_ids(9) 💖