Date: Sat, 18 Aug 2001 01:08:48 -0700 From: Mike Smith <msmith@freebsd.org> To: "Amit Shah" <amitshah@techie.com> Cc: freebsd-arch@freebsd.org Subject: Re: threaded device drivers Message-ID: <200108180808.f7I88mJ08635@mass.dis.org> In-Reply-To: Your message of "Sat, 18 Aug 2001 10:22:19 %2B0500." <20010818052219.5065.qmail@mail.com>
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> I wanted to know if threading of device drivers is supported in freebsd.... i
> f it is not, I would like to do it as a project with some of my colleagues...
> can someone give me some info on this? Also, tell me if it would be benefici
> al (and in what way) to do this on freebsd.
"Threading device drivers" is a bit of an ambiguous description.
There is a lot of abuse of threaded design in device drivers for
operating sytems like Windows; if you're talking about this sort of
thing, then no, it would not be beneficial at all.
The FreeBSD device driver model is very "thin"; drivers don't typically
do very much work, and so code paths tend to run to completion. For
blocking conditions, one typically uses a callback rather than putting a
thread to sleep.
In -current, drivers that want threads can spawn them off; where it's
absolutely necessary it's usually a driver-specific issue rather than
being something that could be implemented in any more generic a fashion.
Regards,
Mike
--
... every activity meets with opposition, everyone who acts has his
rivals and unfortunately opponents also. But not because people want
to be opponents, rather because the tasks and relationships force
people to take different points of view. [Dr. Fritz Todt]
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