linux-kernel - Re: [RFC][PATCH] create workqueue threads only when needed

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Message-ID: <4985DE82.5030208@s5r6.in-berlin.de>
Date:	Sun, 01 Feb 2009 18:40:18 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	Arjan van de Ven <arjan@...radead.org>
CC:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [RFC][PATCH] create workqueue threads only when needed

Arjan van de Ven wrote:
> On Sun, 01 Feb 2009 17:22:47 +0100
> Stefan Richter <stefanr@...6.in-berlin.de> wrote:
>> I have stuff in drivers/firewire/ done in a private workqueue and some
>> in the shared workqueue which I will eventually move either into
>> short-lived ad hoc created kthreads /or/ preferably into a thread pool
>> implementation --- if such a thing will have found its way into the
>> kernel when I have time for my project.
...
> what are the requirements for you to do this?
> 
> right now, the async calls are "fire and forget... but you can wait for
> completion". The "price" is that the code needs to allocate a little
> bit of memory for management overhead. The second price then is that 
> if this allocation fails, the code needs to run "in context".
> 
> Would this be a problem?
> 
> I can add a variant of the API where you pass in some memory of your
> own, which then does not fail. (but also won't get freed automatically
> etc)

I'm not quite sure yet but I believe I can run the work in the current
context if there was an allocation failure, provided those failures are
unlikely.

Hmm.  I don't see the "async/mgr" in the process list of that 2.6.29-rc3
box next to me.  Under which circumstances is this facility available
(long after boot)?  Or am I just barging into a discussion to /make/ it
available after boot?
-- 
Stefan Richter
-=====-==--= --=- ----=
http://arcgraph.de/sr/
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