Notes 2020 12 17

MPI Tools WG Meeting 2020-12-17

Participants

• Wesley Bland
• Chris Chambreau
• Michael Knobloch
• Joachim Protze
• Marc-Andre Hermanns
• Martin Schulz

Topics

• QMPI_Pcontrol

  • Argonne customer wants an interface to communicate different phases of an applications
    • Caliper (LLNL Tool) should be the solution to that

• Pcontrol semantics are terrible to begin with

  • var_list arguments are impossible to intercept

  • MPI_Pvcontrol(const int level, va_list ap)

    • Can easily be intercepted and passed to the next level of QMPI

        int MPI_Pcontrol(const int level, ...){
            va_list args;
        	va_start(args, level);
        	int r = PMPI_Pvcontrol(level, args);
        	va_end(args);
        	return r;
        }

    • Can be different for every compiler
    • Fortran does not have the ...
    • Maybe a key-value store (MPI_Info?, binary values?) could solve this

• Non-blocking version?

  • How to make sure completion can be handled by the library?
    • Something along the lines of the MPI_Pready call to indicate that a tool that intercepts Qcontrol is done manipulating the info object

• Should a tool be required to pass on to next layer?

  • Is this info for me?
    • Exclusively?