Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!fletcher
From: fouts@bozeman.bozeman.ingr (Martin Fouts)
Newsgroups: comp.std.unix
Subject: Re: Standards Update, IEEE 1003.4: Real-time Extensions
Message-ID: <13442@cs.utexas.edu>
Date: 10 Oct 90 17:02:23 GMT
References: <524@usenix.ORG> <528@usenix.ORG> <540@usenix.ORG> <553@usenix.ORG> <13132@cs.utexas.edu> <13156@cs.utexas.edu>
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Submitted-by: fouts@bozeman.bozeman.ingr (Martin Fouts)

>>>>> On 3 Oct 90 17:19:04 GMT, peter@ficc.ferranti.com (Peter da Silva) said:
Peter> In article <13132@cs.utexas.edu> fouts@bozeman.bozeman.ingr (Martin Fouts) writes:
> One reason to not treat every IPC facility as part of the file system:
> Shared memory IPC mechanisms which don't need to be visible to
> processes not participating in the IPC.

Peter> Provide an example, considering the advantages of having shell level
Peter> visibility of objects has for (a) debugging, (b) system administration,
Peter> (c) integration, (d)...

Short persistance IPC mechanisms found in multithreaded shared memory
implementations consist of a small region of memory and a lock guarding
that region.  Producer/consumer parallelism using this mechanism does
not need to be visible.  Effectively, this is the shared memory
equivalent of an unnamed pipe.

a) debugging is handled by the process debugger, not by the shell and
   has the same visibility as any other memory resident data.

b) There is no system administration, since the objects have exactly
   process duration with the same termination semantics as a pipe, in
   that termination of any of the processes is usually catastrophic

c) I'm not sure what integration support would benefit from making
   a short duration object visible.

d) ....

--
Martin Fouts

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Volume-Number: Volume 21, Number 196