HPD -- A High Performance Debugger Implementation

1. HPD -- A High Performance Debugger Implementation A Parallel Tools Consortium project http://www.ptools.org/

2. Work funded by the DoD High Performance Computing Modernization Program, ARL, CEWES, and NAVO Major Shared Resource Centers, through Programming Environment and Training (PET). Views, opinions, and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of Defense position, policy or decision unless so designated by other official documentation.

3. What is HPD? • HPD is an implementation following the standard proposed by The High Performance Debugger Forum. • A debugger for parallel and multi-threaded applications. • Is light weight, easy to use and presents multiprocess/multithread information in a format that is easy to understand.

4. What is the High Performance Debugger Forum? • The Forum was sponsored by The Ptools Consortium • The goals were to define a useful and appropriate set of standards relevant to debugging tools for HPC systems and to accommodate needs of both users and tool developers. • http://www.ptools.org/hpdf/

5. The High Performance Debugger Standard • The standard was written to address the following types of programs: • “high performance” in nature (i.e., performance is an important consideration) and typically parallel • written in one or more high-level languages • intended to run on possibly many different computer systems • The standard assumes explicit parallelism as the basic programming model. • The standard is applicable to both shared-memory programming (multiple threads of execution in an address space) and distributed-memory programming (multiple processes co-operating via message-passing libraries, such as PVM or MPI)

6. The High Performance Debugger Standard • The standard distinguishes the functionality needed for threads-only, process-only and multilevel (multi-process and multi-thread) models of parallelism • The overall objective of the standard is to make it possible for debuggers of all three types to provide support that is consistent as possible, given the constraints imposed by the underlying model. • The major languages considered were Fortran (F77 and F90), C, and C++.

7. Who is doing what • Oregon State University developed the parser for the command line debugger • University of Tennessee is working on implementing the rest of the debugger and writing the DBX client • University of Tennessee and Robert Hood from NASA are working on making the p2d2 internal code modular so it can be used in this project as a basis for HPD.

8. Implementation Details • There are several layers to make the implementation modular: • Front-end (e.g. command line, GUI ) • Data Management Layer • Debugger Server Layer • Client Layer (e.g. GDB, DBX, etc…) • The Data Management Layer contains all the group and process information.

9. Implementation Details (cont.) • The client layer parses output, sends the commands to the various debuggers. • Each process will have one debugger attached to it. The control of these debuggers will be through the front-end

10. p2d2/HPD’s Client-server Architecture remote server a.out user interface distribution manager debugger server remote server a.out client remote server a.out

11. What will the beta release contain (est. Feb 99)? • A subset version of the command line debugger implementing the following: • run, continue, break, print, where • Due to memory issues run will only work the first time you use it, then you must exit out and restart the debugger • GDB will be the only debugger supported initially.

12. Future Work • DBX as the per-process debugger • Add functionality to implement as much of the standard as possible • Memory clean-up routines • Make the code more modular

13. For More Information • http://icl.cs.utk.edu/projects/hpd/ • http://www.ptools.org/ • http://www.ptools.org/hpdf/ • http://www.ptools.org/hpdf/draft/