idle_worker_timeout(9)

💅 idle_worker_timeout(9) 💅

okay bestie, we're deep in the Kernel API Manual today — yes, that manual, the one with the big workqueue lore. sit down, hydrate, this one's a little timer callback and it's lowkey iconic 🎀

---

✨ NAME ✨

idle_worker_timeout — check if some idle workers can now be deleted. fr fr that's the whole job. it's giving "uninvited guest doing the vibe check at the door" 🚪💅

---

🌸 SYNOPSIS 🌸

void idle_worker_timeout (struct timer_list *t );

---

🦋 ARGUMENTS 🦋

• t — the pool's idle_timer that just expired. like, it literally just went off, and now it's here asking for attention 🫶

---

🔥 DESCRIPTION 🔥

okay so the timer gets armed in worker_enter_idle. that's the setup, that's the glow-up moment, that's when the clock starts 👑

but here's the twist — it is not disarmed in worker_leave_idle. and ngl that's on purpose, bestie 😭

the reason? a worker flicking between idle and active while its pool is sitting at the too_many_workers tipping point would cause too much timer housekeeping overhead. like, imagine arming and disarming and arming and disarming — the CPU said "not me doing all that" 💀 so we just don't.

and since IDLE_WORKER_TIMEOUT is long enough (it's long, she's patient, she's got main character energy ✨), we just let it expire and re-evaluate things from there. no micromanaging. no cap. we let the timer cook, then we look around and re-decide. periodt 🌈

bestie note: the "don't disarm" thing isn't a bug, it's a deliberate trade-off. do not go "fixing" it 🙈

---

👑 SEE ALSO 👑

so many friends, so little time 🫶 first up, the kernel file itself — ./kernel/workqueue.c — and then the whole group chat:

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_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), precompute_cache_shard_ids(9), workqueue_init_topology(9) 💖

---

mwah, that's the page 💜 this little drop came out of ./kernel, dated October 2026 — so go forth, let the timer expire, and re-evaluate your life from there 🧚✨