Date: Tue, 07 Nov 2000 13:21:27 -0800 From: Julian Elischer <julian@elischer.org> To: Randell Jesup <rjesup@wgate.com> Cc: "Justin T. Gibbs" <gibbs@scsiguy.com>, Matt Dillon <dillon@earth.backplane.com>, Poul-Henning Kamp <phk@critter.freebsd.dk>, Bruce Evans <bde@zeta.org.au>, Kirk McKusick <mckusick@mckusick.com>, arch@FreeBSD.ORG Subject: Re: softdep panic due to blocked malloc (with traceback) Message-ID: <3A087257.DBA40791@elischer.org> References: <200011072021.eA7KLKa57382@aslan.scsiguy.com> <ybur94ntsh8.fsf@jesup.eng.tvol.net.jesup.eng.tvol.net>
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Randell Jesup wrote:
>
> "Justin T. Gibbs" <gibbs@scsiguy.com> writes:
> >That's not what Poul-Henning was attempting to convey. If you are near the
> >edge, you need to make sure you don't fall off the edge. That is
> >the jist of your changes. Poul-Henning's request was for a facility
> >to possibly give you more space near the edge to work your way away
> >from it. In otherwords, you might thrash less or recover more quickly
> >from a low memory situation if you tell the rest of the kernel to free
> >up data that can be recreated on demand.
>
> I think both Matt's changes and what Poul-Henning can be useful.
> (Actually, it sounds like Matt's are required, and Poul-Henning's might be
> nice if and when someone does them).
I think that they are talking with cross purposes..
Matt is right that nothing that magically comes up with a few hundred KB
of ram
can be guaranteed to stop a deadlock, because after the few hundred KB
have been
used up, If the big memory hog keeps eating memory, you are right back
where you
started, and you no longer have a few hundred KB up your sleeve.
On the other hand, PHK is correct in that it would be a useful facility
to have and that it might buy some breathing space. To be ueful however
I think it
would need to be combined with some other measures to ensure that we
don't get straight
back into debt. For example triggering that queue might change the
strategies in the
kernel so that the biggest memory users are forced to start losing
pages.
(e.g. it's swapped out) or some similar work..
>
> IMHO
>
> --
> Randell Jesup, Worldgate Communications, ex-Scala, ex-Amiga OS team ('88-94)
> rjesup@wgate.com
>
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( OZ ) World tour 2000
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