Path: utzoo!attcan!uunet!tut.cis.ohio-state.edu!zaphod.mps.ohio-state.edu!samsung!munnari.oz.au!sirius.ucs.adelaide.edu.au!augean!sibyl!ian
From: ian@sibyl.eleceng.ua.OZ (Ian Dall)
Newsgroups: comp.arch
Subject: Re: vfork (was Re: Paging page tables)
Message-ID: <781@sibyl.eleceng.ua.OZ>
Date: 20 Jul 90 02:08:09 GMT
References: <920@dgis.dtic.dla.mil> <5830@titcce.cc.titech.ac.jp> <5DL4SPD@xds13.ferranti.com> <5855@titcce.cc.titech.ac.jp> <774@sibyl.eleceng.ua.OZ> <5891@titcce.cc.titech.ac.jp>
Reply-To: ian@sibyl.OZ (Ian Dall)
Organization: Engineering, Uni of Adelaide, Australia
Lines: 34

In article <5891@titcce.cc.titech.ac.jp> mohta@necom830.cc.titech.ac.jp (Masataka Ohta) writes:
>No. I live in a unary world of BSD UNIX.

Even worse. Use your imagination, there *are* other ways of doing things.
No, I am not bitching about BSD in general, on balance I would much prefer
it to SysV, but you have to look at each idea on it's merits.

>>To the user the
>>system will appear to have deadlocked, but not to the super user who
>>can at least run ps and kill.
>
>It is not a solution.

Why not? My suggestion was that if total virtual memory requirements
exceeded some threshold then only "priviledged" processes could do
anything which increased their virtual memory requirements. If we
define "priviledged" as, say, uids less than 100 (belonging to some
group would probably be better) then all your "important system
processes" continue to run which as I recall was your chief problem.

Depending on exactly what signal handling the user processes use, he
might still be able to kill them with ^C. Also remember that this
"frozen to ordinary users" state doesn't occur until the virtual
memory requirements exceeds highwater(physical memory + swap space),
ie after a current preallocating BSD system would have ceased to work
anyway, I can't see what your objection is.

Saying it is not a solution does not make it so. If you have any
reasonable objection to the scheme, then detail it.


-- 
Ian Dall     life (n). A sexually transmitted disease which afflicts
                       some people more severely than others.