linux-kernel - Re: [PATCH] workqueue: don't alloc

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Date:	Wed, 21 Jan 2009 11:48:11 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Lai Jiangshan <laijs@...fujitsu.com>
Cc:	Oleg Nesterov <oleg@...sign.ru>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] workqueue: don't alloc_percpu for single workqueue


* Lai Jiangshan <laijs@...fujitsu.com> 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.

	Ingo

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
CHECKPATCH in MAINTAINERS.
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