Notes 2020 04 16

Meeting 2020-04-16

Participants

• Joachim Protze
• Kathryn Mohror
• Bengisu Elis
• Josh Cottingham
• Marc-Andre Hermanns

Topics

Handle Introspection interface by Open MPI

• Handle Introspection Header available in Open MPI

  • ompi/debuggers/mpihandles_interface.h
  • It re-uses the callbacks and terms of the message queue interface

• Architecture of MQD is similar to what we need here (Figure 4.1)

• External Library has a set of query functions

  • Number of Compicators
  • Next communicator

• We may reuse the infrastructure of MQD

  • Could be implemented in the same DLL (just more functions)

• Should we have specific query functions for specific information?

  • DLL can easily return specific values even if not all information is stored in a compact manner
  • In OMPD: just ask for specific information of interest
  • Workflow:
  • 1. Ask for a debugging handle that represents an MPI handle
    2. In this debugging handle DLL can cache information by and by

• We would need the same set of functions for each handle type

  • Currently only comm, request, status
  • Interesting types: win, datatype, op

• Should we integrate it into mqs?

  • What about the function prefix mqs_
  • Maybe better have a new interface that allows MQD to be expressed in that new interface
  • Some functions of MQD might be difficult to implement without debugging information
    • type size and field offsets
  • In OMPD such values are stored in global variables
    • is available even without debugging symbols