Path: utzoo!mnetor!uunet!husc6!think!barmar
From: barmar@think.COM (Barry Margolin)
Newsgroups: comp.unix.wizards
Subject: Re: Shared Memory in BSD4.3 is lacking?
Message-ID: <17584@think.UUCP>
Date: 5 Mar 88 19:40:20 GMT
References: <12137@brl-adm.ARPA>
Sender: usenet@think.UUCP
Reply-To: barmar@fafnir.think.com.UUCP (Barry Margolin)
Organization: Thinking Machines Corporation, Cambridge, MA
Lines: 25

In article <12137@brl-adm.ARPA> rbj@icst-cmr.arpa (Root Boy Jim) writes:
>   Trivia bowl time (related to another comp.unix.wizards topic).  Some have
>   argued that a great way to access shared-memory regions is through the
>   filesystem namespace.  Well, there is at least one operating system out
>   there that does just that.  Which OS is that?
>   [sound of Jeopardy theme music...]

Multics, for at least a decade longer than VMS.  In fact, the only way
to access files on Multics is to map them onto memory segments.  And
if two processes happen to map the same file they get shared memory.
Shared binaries are also a natural result of this, and coupled with
dynamic linking you also get shared libraries.

In a couple of decades Unix will finish living up to its progenitor's
expectations.

I believe TOPS-20 also allows processes to map files into their
address space and get shared memory that way.


Barry Margolin
Thinking Machines Corp.

barmar@think.com
uunet!think!barmar