linux-kernel - Re: [PATCH 4/7 V6] workqueue: fix idle worker depletion

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Message-ID: <20120908190204.GA12773@dhcp-172-17-108-109.mtv.corp.google.com>
Date:	Sat, 8 Sep 2012 12:02:04 -0700
From:	Tejun Heo <tj@...nel.org>
To:	Lai Jiangshan <eag0628@...il.com>
Cc:	Lai Jiangshan <laijs@...fujitsu.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7 V6] workqueue: fix idle worker depletion

Hello, Lai.

On Sun, Sep 09, 2012 at 02:34:02AM +0800, Lai Jiangshan wrote:
> in 3.6 busy_worker_rebind() handle WORKER_REBIND bit,
> not WORKER_UNBOUND bit.
>
> busy_worker_rebind() takes struct work_struct *work argument, we have to
> add new patch to add a helper and restruct it at first.

What's wrong with just treating manager as busy.  Factor out,
rebind_work scheduling from rebind_workers() and call it for busy
workers and the manager if it exists.  manage_workers() only need to
call process_scheduled_works().  Wouldn't that work?

> worker_maybe_bind_and_lock() 's mean is very clear
> here. busy_worker_rebind() seems for busy workers, manager is not
> busy workers.

I don't know.  It just seems unnecessarily wordy.  If you don't like
reusing the busy worker path, how about just calling
maybe_bind_and_lock() unconditionally after locking manager_mutex?  I
mean, can't it just do the following?

	spin_unlock_irq(&gcwq->lock);

	/*
	 * Explain what's going on.
	 */
	mutex_lock(&pool->manager_mutex);
	if (worker_maybe_bind_and_lock(worker))
		worker_clr_flags(worker, WORKER_UNBOUND);
	ret = true;

Thanks.

-- 
tejun
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