From owner-freebsd-arch  Fri Dec  1 18: 6:28 2000
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Date: Fri, 1 Dec 2000 18:06:22 -0800 (PST)
From: Matthew Jacob <mjacob@feral.com>
Reply-To: mjacob@feral.com
To: David Greenman <dg@root.com>
Cc: Andrew Gallatin <gallatin@cs.duke.edu>,
	Bosko Milekic <bmilekic@technokratis.com>,
	"Kenneth D. Merry" <ken@kdm.org>, arch@FreeBSD.ORG,
	alfred@FreeBSD.ORG
Subject: Re: zero copy code review 
In-Reply-To: <200012020202.SAA14681@implode.root.com>
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> >
> >> 
> >> David Greenman writes:
> >>  >    Oops. The original assumption (and code that I wrote) was that M_WAIT
> >>  > _cannot_ return a NULL pointer. This was changed in FreeBSD recently, and
> >> 
> >> Yes, that's always been my assumption too.  That's why I never noticed
> >> it...
> >
> >IIRC, this has never been guaranteed. It's often unlikely that a request can't
> >be satisfied after a sleep with the current code.
> 
>    FreeBSD blocked indefinitly and never returned a NULL pointer.

Smells like livelock somewhere here, but has it changed recently as has been
asserted?




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