Re: [PATCH] workqueue: don't alloc_percpu for single workqueue

From: Ingo Molnar
Date: Wed Jan 21 2009 - 05:48:38 EST

* Lai Jiangshan <laijs@xxxxxxxxxxxxxx> wrote:

> allocating memory for every cpu for single workqueue is waste.

good idea.

One detail:

> @@ -906,6 +907,13 @@ void destroy_workqueue(struct workqueue_struct *wq)
> const struct cpumask *cpu_map = wq_cpu_map(wq);
> int cpu;
> + if (is_wq_single_threaded(wq)) {
> + cleanup_workqueue_thread(wq->cpu_wq);
> + kfree(wq->cpu_wq);
> + kfree(wq);
> + return;
> + }
> +
> cpu_maps_update_begin();
> spin_lock(&workqueue_lock);
> list_del(&wq->list);

Arent we forgetting to remove the workqueue from the &workqueues list in
the new single-thread case?

Also, see the checkpatch output from kernel/workqueue.c - the warnings
below are correct and should be cleaned up.


WARNING: printk() should include KERN_ facility level
#268: FILE: workqueue.c:268:
+ printk("%s: recursion depth exceeded: %d\n",

ERROR: code indent should use tabs where possible
#304: FILE: workqueue.c:304:
+^I^I^I^I ^Itask_pid_nr(current));$

ERROR: "foo* bar" should be "foo *bar"
#555: FILE: workqueue.c:555:
+ struct timer_list* timer)

ERROR: code indent should use tabs where possible
#916: FILE: workqueue.c:916:
+ ^Icpu_maps_update_done();$

kernel/workqueue.c has style problems, please review. If any of these errors
are false positives report them to the maintainer, see
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