Message-ID: <40CF74C0.1040409@pobox.com>
Date: Tue, 15 Jun 2004 18:14:24 -0400
From: Jeff Garzik <jgarzik@pobox.com>
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To: Jesse Barnes <jbarnes@engr.sgi.com>, Dean Nelson <dcn@sgi.com>
CC: Arjan van de Ven <arjanv@redhat.com>, linux-kernel@vger.kernel.org,
       rusty@rustcorp.com.au
Subject: Re: calling kthread_create() from interrupt thread
References: <40CF350B.mailxD2X1NPFBC@aqua.americas.sgi.com> <1087321777.2710.43.camel@laptop.fenrus.com> <20040615180525.GA17145@sgi.com> <200406151414.20565.jbarnes@engr.sgi.com>
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Jesse Barnes wrote:
> On Tuesday, June 15, 2004 2:05 pm, Dean Nelson wrote:
> 
>>As mentioned above, it is possible for this "simple" function to
>>sleep/block for an indefinite period of time. I was under the impression
>>that one couldn't block a work queue thread for an indefinite period of
>>time. Am I mistaken?
> 
> 
> For tasklets and softirqs you're not allowed to sleep, but I think it's ok for 
> work queues.


Dean is correct and incorrect ;-)

If you are using schedule_work() or schedule_task(), blocking for 
extended periods of time would be very undesirable.  We see this on 
occasion in 2.6 uniprocessor, where a long-running keventd task may 
block a console or tty update.

In 2.6, the solution is easy... create your own private workqueue.  No 
such solution in 2.4 (though I would argue that workqueues would help 
drivers, if accepted into 2.4 at this late stage).

	Jeff


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