From owner-freebsd-hackers  Tue Mar 26 12: 4:43 2002
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Date: Tue, 26 Mar 2002 12:03:10 -0800
From: Terry Lambert <tlambert2@mindspring.com>
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To: Dan Nelson <dnelson@allantgroup.com>
Cc: Andrew <andrew@ugh.net.au>,
	Volker Stolz <stolz@hyperion.informatik.rwth-aachen.de>,
	Ian <freebsd@damnhippie.dyndns.org>, hackers@FreeBSD.ORG
Subject: Re: idprio
References: <20020326121046.A3952@margaux.informatik.rwth-aachen.de> <20020326232510.A21338-100000@starbug.ugh.net.au> <20020326153541.GF17825@dan.emsphone.com>
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Dan Nelson wrote:
> In the last episode (Mar 26), Andrew said:
> > On Tue, 26 Mar 2002, Volker Stolz wrote:
> > > Under FreeBSD system calls are currently never preempted, therefore
> > > non- realtime processes can starve realtime processes, or idletime
> > > processes can starve normal priority processes.
> >
> > Even so an idprio process can't be worse than a normal process.
> 
> Sure it can, if the idprio process has locked a vnode trying to update
> the contents of a file, and another non-idprio process starts consuming
> 100% CPU.  The idprio process never gets a chance to run again, and if
> that vnode happened to be an important one (say for /), you may not be
> able to kill the other process without rebooting.

You meant that when you use priorities, you risk priority inversion?

8-p

-- Terry

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