The objective of the MPI profiling interface is to ensure that it is relatively easy for authors of profiling (and other similar) tools to interface their codes to MPI implementations on different machines. layeringlibraries
Since MPI is a machine independent standard with many different implementations, it is unreasonable to expect that the authors of profiling tools for MPI will have access to the source code which implements MPI on any particular machine. It is therefore necessary to provide a mechanism by which the implementors of such tools can collect whatever performance information they wish without access to the underlying implementation.
The MPI Forum believed that having such an interface is important if MPI is to be attractive to end users, since the availability of many different tools will be a significant factor in attracting users to the MPI standard.
The profiling interface is just that, an interface. It says nothing about the way in which it is used. Therefore, there is no attempt to lay down what information is collected through the interface, or how the collected information is saved, filtered, or displayed.
While the initial impetus for the development of this interface arose from the desire to permit the implementation of profiling tools, it is clear that an interface like that specified may also prove useful for other purposes, such as ``internetworking'' multiple MPI implementations. Since all that is defined is an interface, there is no impediment to it being used wherever it is useful.
As the issues being addressed here are intimately tied up with the way
in which executable images are built, which may differ greatly on
different machines, the examples given below should be treated solely
as one way of implementing the MPI profiling
interface. The actual requirements made of an implementation are those
detailed in Section 
, the whole of the rest of
this chapter is only present as justification and discussion of the
logic for those requirements.
The examples below show one way in which an implementation could be constructed to meet the requirements on a Unix system (there are doubtless others which would be equally valid).