Re: teraspace, user spaces, etc.

["M. Lazarus" <mlazarus@xxxxxxxx>]

Paul,

At 5/23/01 07:05 AM -0500, you wrote:
>Perhaps the high level of abstraction is frustrating for
>those who want to know the underlying details, but such abstraction is
>required for adaptability. Giving out details below the published level of
>abstraction would make change much more difficult, because then
>dependencies on one particular implementation could be developed.

  In theory, I agree w/ the above statement, but in practice I 
disagree.  MI programmers have always known that a release or even a PTF 
can break their code.  This is one of the risks of this type of programming.

  The reasons to know about and utilize low-level functions are numerous, 
but a few come to mind immediately:

1)  Performance.  Sometimes, for whatever reason, the supported interface 
will not perform a particular task quickly enough.  This may be an unusual 
scenario that IBM will address, due to the circumstances.

2)  Functionality.  All of the functionality of a particular function may 
not be exposed by the official interface.  Case in point are the 
trigonometric functions that have been directly available in MI since day 
one, but only since the inception of ILE can they be directly accessed via 
the HLLs.

3)  There are many smart people out there that can give the good folks in 
IBM labs some implementation ideas and feedback.


  -mark

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