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From: "John S. Dyson" <toor@dyson.iquest.net>
Message-Id: <199612101424.JAA06928@dyson.iquest.net>
Subject: Re: Multiple Buffer allocation of Shared Memory
To: erich@lodgenet.com (Eric L. Hernes)
Date: Tue, 10 Dec 1996 09:24:21 -0500 (EST)
Cc: dyson@FreeBSD.ORG, erich@lodgenet.com, scrappy@hub.org,
        hackers@FreeBSD.ORG
In-Reply-To: <199612101407.IAA05255@jake.lodgenet.com> from "Eric L. Hernes" at Dec 10, 96 08:07:39 am
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> >The limits on FreeBSD are totally administrative, and so if you need to
> >increase SHMMAXPGS or somesuch, there is little cost.
> >
> 
> Are there any big obstacles to making this totally dynamic?
> 
None that I know of.  Mapping the shared memory into kva space seperately
from process space (like the original code) is of no use, and takes
KVA space.  When it takes KVA space, there becomes a problem with
KVA space allocation.  The only limitation(s) on FreeBSD, other
than administative are (I think) process size, and swap space.

FreeBSD has used the NetBSD code since the 4.4-lite re-do.  When we
had users complain about the shared memory size limits, I was suprised
that the code was implemented to use KVA space?!?!?  The mods aren't
that hard to fix it.

There are some other nits that I have about the code, and I have it partially
rewritten (smaller) from scratch.  But, it isn't my highest priority right
now, and the current code in FreeBSD (modified NetBSD code) works ok.

John