Path: utzoo!mnetor!uunet!husc6!mailrus!ames!pioneer!pstevens
From: pstevens@pioneer.arpa (Paul Stevens RCE Sterling)
Newsgroups: comp.os.vms
Subject: Re: INSTALLED IMAGE question
Message-ID: <8266@ames.arpa>
Date: 4 May 88 14:46:09 GMT
References: <12395117720.16.STEINBERGER@KL.SRI.COM> <5077@bloom-beacon.MIT.EDU>
Sender: usenet@ames.arpa
Reply-To: pstevens@pioneer.UUCP (Paul Stevens RCE Sterling)
Organization: NASA Ames Research Center, Moffett Field, Calif.
Lines: 27

In article <5077@bloom-beacon.MIT.EDU> tada@athena.mit.edu (Michael Zehr) writes:
>
>Does anyone know how this applies to data files?  I want two processes
>to run at the same time, each of them reading data from a file.  I can
>install the file /open, but when i try it /shared, it complains (BADHDR
>-- an error was discovered in the image header).  The machine is
>really thrashing for memory, so any suggestions on how to make the
>processes share data pages would be appreciated.
>
I believe that to install as SHARED the file must be an executable.
To do what you want, look at $CRMPSC (create and map section system
service) and use it to create a permanant section.  Of course you will
need suficient privledges to do so.  Of course, with both techniques the
file will only actually be in memory after one or more processes maps to
it.  It's also possible to accomplish the same thing (sharing a data file
between two processes) by using linker options, but then your file must be
source code for some supported language, as opposed to raw data.  Hope this
helps a bit.




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Paul Stevens - NASA Ames Research Center Moffet Field CA
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