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From: stripes@eng.umd.edu (Joshua Osborne)
Newsgroups: comp.unix.wizards
Subject: Re: Checkpoint/Restart (was "no subject - file transmission")
Keywords: Checkpoint
Message-ID: <1990Aug18.194534.17408@eng.umd.edu>
Date: 18 Aug 90 19:45:34 GMT
References: <24193@adm.BRL.MIL> <13611@smoke.BRL.MIL> <17543@ucsd.Edu>
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Organization: College of Engineering, Maryversity of Uniland, College Park
Lines: 33


In article <17543@ucsd.Edu> gkn@ucsd.Edu writes:
[...]
>I think it's a bit unfair for every user of a system to have to
>invent a way to do this specific to their particular application.
>In many cases it may not be possible (the above "canned software"
>problem being an example).

Yes it is.  That's why the people who write the application should do it.
If the OS comes with a package that can do a large part of the work for the
application then the writer will be more likely to do it, but there is no
way the OS can do it.  For example a program that runs on jolt that
does lots of number crunching & sometimes feeds number to coke and sometimes
gets numbers from pepsi.  How could any program that exists only on jolt
handle this?  It has to get coke & pepsi (which may not run the same Unix,
or may not even run Unix) to save that state of whatever the process on
jolt is talking to.  Not very possable.

>I agree that adding this capability to many varieties of Unix may
>require much skull sweat, especially to get it right.  But in the
>environment here at SDSC (and in other places) checkpointing is a
>remarkably useful feature.

No, not skull sweat.  Impossable.
Not 100% impossable, but 10% impossable.  Things that talk to the network
are for the OS to save.  Things that talk to other processes are hard to
save.
-- 
           stripes@eng.umd.edu          "Security for Unix is like
      Josh_Osborne@Real_World,The          Mutitasking for MS-DOS"
      "The dyslexic porgramer"                  - Kevin Lockwood
"Is that a shell script?"                                 - David J. MacKenzie
"Yeah, kinda sticks out like a sore thumb in the middle of a kernel" - K. Lidl