Message-ID: <4C18D1FD.9060804@kernel.org>
Date: Wed, 16 Jun 2010 15:30:37 +0200
From: Tejun Heo <tj@kernel.org>
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To: Daniel Walker <dwalker@codeaurora.org>
CC: mingo@elte.hu, awalls@radix.net, linux-kernel@vger.kernel.org,
       jeff@garzik.org, akpm@linux-foundation.org, rusty@rustcorp.com.au,
       cl@linux-foundation.org, dhowells@redhat.com, arjan@linux.intel.com,
       johannes@sipsolutions.net, oleg@redhat.com, axboe@kernel.dk
Subject: Re: Overview of concurrency managed workqueue
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On 06/16/2010 03:27 PM, Daniel Walker wrote:
>> Yes, that is.  With new cmwq, a wq can't assume association with
>> specific kthread and thus can't use wq as simple frontend to kthreads,
>> but if somebody wants dedicated kthreads instead of shared ones in
>> units of work, [s]he should be using kthread.
> 
> I'm not talking about coders using workqueues when they should be using
> kthreads .. We're talking about currently existing workqueues. Aren't
> you converting all _current_ workqueues to your system?

Yes, sure I'm but which current users are you talking about?

>> wq does provide nicer tools for synchronization but in general I don't
>> think using kthread is too hard and there aren't too many cases
>> anyway.  If there are many users && kthread is difficult to use
>> directly, we can definitely write up a wrapping layer tho.  But I
>> really think using wq as wrapper around kthreads and manipulating
>> worker thread directly is an abusement.
> 
> It would be a hack the user would have to patch onto there kernel in
> order to get back functionality your taking away.
> 
> I think from your perspective workqueue threads are all used for
> "concurrency management" only, but I don't think that's true. Some will
> be user for prioritization (I'm talking about _current_ workqueues).
> 
> Could you address or ponder how the work items could be prioritized
> under your system?

Again, please give me some examples.

Thanks.

-- 
tejun
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