linux-kernel - Re: [PATCH 02/11 V5] workqueue: async idle rebinding

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Message-ID: <5047FC43.2020706@cn.fujitsu.com>
Date:	Thu, 06 Sep 2012 09:28:35 +0800
From:	Lai Jiangshan <laijs@...fujitsu.com>
To:	Tejun Heo <tj@...nel.org>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/11 V5] workqueue: async idle rebinding

On 09/06/2012 02:06 AM, Tejun Heo wrote:
> Hello, Lai.
> 
> Ooh, I like the approach.  That said, I think it's a bit too invasive
> for 3.6-fixes.  I'll merge the two patches I posted yesterday in
> 3.6-fixes.  Let's do this restructuring in for-3.7.

OK for me.
it is too complicated for 3.6.

> 
> On Wed, Sep 05, 2012 at 06:37:39PM +0800, Lai Jiangshan wrote:
>>  static void idle_worker_rebind(struct worker *worker)
>>  {
>>  	struct global_cwq *gcwq = worker->pool->gcwq;
>>  
>> -	/* CPU must be online at this point */
>> -	WARN_ON(!worker_maybe_bind_and_lock(worker));
>> -	if (!--worker->idle_rebind->cnt)
>> -		complete(&worker->idle_rebind->done);
>> -	spin_unlock_irq(&worker->pool->gcwq->lock);
>> +	if (worker_maybe_bind_and_lock(worker))
>> +		worker_clr_flags(worker, WORKER_UNBOUND);
>>  
>> -	/* we did our part, wait for rebind_workers() to finish up */
>> -	wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND));
>> +	worker_clr_flags(worker, WORKER_REBIND);
>> +	list_add(&worker->entry, &worker->pool->idle_list);
>> +	spin_unlock_irq(&gcwq->lock);
> 
> This looks correct to me but it's still a bit scary.  Some comments
> explaining why the above is correct would be nice.

How to explain the correct, could you give some clues.
correctness for rebinding and the flags: comments is missing. (old code miss it too, so I forgot it)
correctness for idle management: list_del_init() and list_add(), I don't like to add comment for slef-explain-code.
correctness for quick-enabled-CMWQ, local-wake-up: comments is in the changelog. (I should also add it to the code)
correctness for integrating of above: ..

> 
> Yeah, other than that, looks good to me.  I'll prepare new for-3.7
> branch this can be based on, so please wait a bit.  Also, I think I'll
> probably update commit description / comments while committing.
> 

I was coding it based on wq/for-3.7. so you can merge it easier.
waiting for you merged-result.

Thanks.
Lai

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