Re: Efficiency of Bound vs. Dynamic Calls

[John P Carr <jpcarr@xxxxxxxxxxxx>]

>Yes and the single level store is something I have been trying to wrap my
>mind around. Is there a white paper or patent document that states what it
>really is. I would imagine that the service program's image would have to
be
>mapped into the process's memory space..
>Thanks for the correction!
>Eric Wilson


Eric

Real quick, and I don't mean this to be a NET (the Thread version of a NEP
if you know what that is)

Single Level Store,   Every object created on the AS/400 will only have One 
address space assigned to it(at creation) for its life.   Actually longer.

If you call a Program, (etc any object) and I call that same program a
second 
later we will both "Branch  to / be resolved to "  the very same virtual
address.

We will have our own variables unique to our job,  but the object code of 
the program itself - will be shared by all processes on the machine.  

So Service programs and regular old dynamic calls to programs (if they
are used by lots of people)  may indeed be resident in memory all 
day long after the first call.    So after the first call,  no one else will
incur the
bring from Dasd cost.    Same is true for files, until the last person on
the 
machine using that file closes it,  its structure is in memory. 

Above I said "actually longer"  because unlike most every other virtual
machine(mainframes etc.)   where the virtual address space is carved 
up at IPL,  our machine has persistence in its truest form.   Machine on,
machine off,  the object has the same address.    Now,  When you 
destroy an object(DLTPGM, etc)  Those virtual addresses for that
object will never be assigned again.   They will be "tagged" as invalid.

Some of the "Viruses" on other machines where one process gets the 
handle for an address space,   hold it,  and another process(or same) 
destroys that object,   You have control over that address space and 
you can do harm.   Ah,  you can't do that here.

So,  Thoses dynamic calls (with *INLR left *OFF) might not be that
bad if you "Design In"  object code sharing when designing at a System 
level.   

End of lession,
John Carr

(Classes by Powertech  visit www.400school.com)


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