Subject: Re: suggestion for changes in 5.5

From: [email-masked] (Tom Henderson)
Date: Wed, 5 Jan 94 09:12:53 MST

Lyndon writes:

> One thought which comes to mind, MPI demands that the program creation
> environment at  least allow  SPMD  program creation,  perhaps we could
> make the inclusion  of  name server(s) a mandated run time _option_ in
> program creation environment (possibly also a link time option).  This
> way if you dont want it you dont get it, and if you do want it you say
> you want it and you get it.

Would it be possible to specify this at run time in the call to MPI_INIT()?  
Maybe an additional argument like:  

C  "I don't need a name service."
      CALL MPI_INIT(MPI_INIT_DEFAULT)
...

C  "I want the name service."
      CALL MPI_INIT(MPI_INIT_NAME_SERVICE)
...

If this could work, it seems cleaner to me.  

> The detailed  suggestion  does have  some abstract  elegance,  and  it
> removes  the function  MPI_INTERCOMM_NAME  while  retaining  a  "name"
> service capability in which "name" is a non-negative integer. However,
> what does  the  proposal do for us?  It  removes the string name which
> after all was more convenient for the user (loss) for what seems to be
> a very small decrease in the complexity of implementation (gain). Is it
> worth making this change?

I feel that the change is not worth it here.  I'd like to see more 
discussion...  

Tom

---

From: [email-masked] (James Cownie)
Date: Wed, 5 Jan 1994 16:20:46 +0000

> Would it be possible to specify this at run time in the call to MPI_INIT()?  

This is clearly possible. It has some cost, however, in that all the
name service code has to be present whether or not it is going to be
used. 

I don't have a problem with this on my machine, it can all go in a
dynamic shared library and appear as needed, so it takes no space
until it is used.

However I think there may be other people who are concerned about
executable size and don't have such a rich run time environment. In
this case all that code has to be loaded (onto every node too if it's
really a SPMD code !), and it begins to seem rather costly...

-- Jim 
James Cownie 
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