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Date: Mon, 27 May 2013 10:09:28 +0300
From: Andriy Gapon <avg@FreeBSD.org>
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To: Konstantin Belousov <kostikbel@gmail.com>
Subject: Re: preemptive kernel
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Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@FreeBSD.org>,
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on 27/05/2013 09:34 Konstantin Belousov said the following:
> Having both filter and ithread for the same interrupt is apparently
> possible but weird.  I do not see anything which would prevent interrupt
> filter from being executed while the ithread is running.  But again, this
> is very unusual setup.

I wouldn't call it weird, but, yes, it is rare.  It's a pretty normal
configuration when the filter acts as a filter and the handler acts as a
handler (in ithread).  In other words, it would be a replacement for a
configuration where a filter is used and the filter offloads actual work to
non-interrupt context via a e.g. taskqueue.
But, hmm, this functionality is probably locked under INTR_FILTER option.

-- 
Andriy Gapon