From owner-freebsd-hackers  Sun Mar 31 11:45:29 2002
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Date: Sun, 31 Mar 2002 13:46:08 +0000
From: Josh Paetzel <friar_josh@webwarrior.net>
To: Terry Lambert <tlambert2@mindspring.com>
Cc: Alfred Perlstein <bright@mu.org>, Andrew <andrew@ugh.net.au>,
	Dan Nelson <dnelson@allantgroup.com>,
	Volker Stolz <stolz@hyperion.informatik.rwth-aachen.de>,
	Ian <freebsd@damnhippie.dyndns.org>, hackers@FreeBSD.ORG
Subject: Re: idprio
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References: <3CA0D3FE.8113515C@mindspring.com> <20020327092520.V24232-100000@starbug.ugh.net.au> <20020326223103.GC93885@elvis.mu.org> <3CA156F5.79580CE3@mindspring.com>
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In-Reply-To: <3CA156F5.79580CE3@mindspring.com>; from tlambert2@mindspring.com on Tue, Mar 26, 2002 at 09:21:57PM -0800
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On Tue, Mar 26, 2002 at 09:21:57PM -0800, Terry Lambert wrote:
> Alfred Perlstein wrote:
> > > But if system calls aren't preempted under what circumstances can a
> > > process hold a vnode lock and then be usurped for processor?
> > 
> > While sleeping for IO.
> 
> Ideal systems release and reacquire locks when they are going
> to suspend for a long time (Djikstra's "Banker's Algorithm").
> 
> -- Terry
> 

Of course, the downside of this is that a low priority process that 
needs a lot of resources may never be able get all of the resources 
that it needs.  :)

Josh

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