1. Performance Technology for Complex Parallel Systems Part 2 – Complexity Scenarios Sameer Shende

2. SC’01 Tutorial Nov. 7, 2001 Goals  Explore performance analysis issues in different parallel computing and programming contexts  Demonstrate TAU’s usage in different parallel application case studies  Explore ways to bridge the semantic gap between entities that tools present and the user’s abstractions  Highlight TAU performance mapping API

3. SC’01 Tutorial Nov. 7, 2001 Complexity Scenarios  Message passing computation  Observe message communication events  Associate messaging events with program events  SPMD applications with multiple procesess  SIMPLE hydrodynamics application (C, MPI)  Multi-threaded computation  (Abstract) thread-based performance measurement  Multi-threaded parallel execution  Asynchronous runtime system scheduling  Multi-threading performance analysis in Java

4. SC’01 Tutorial Nov. 7, 2001 Complexity Scenarios (continued)  Mixed-mode parallel computation  Portable shared memory and message passing APIs  Integrate messaging events with multi-threading events  OpenMP + MPI, Java + MPI  Object-oriented programming and C++  Object-based performance analysis  Performance measurement of template-derived code  Array classes and expression transformation  Hierarchical parallel software and module composition  Multi-level software framework and work scheduling  Module-specific performance mapping

5. SC’01 Tutorial Nov. 7, 2001 Strategies for Empirical Performance Evaluation  Empirical performance evaluation as a series of performance experiments  Experiment trials describing instrumentation and measurement requirements  Where/When/How axes of empirical performance space  where are performance measurements made in program  when is performance instrumentation done  how are performance measurement/instrumentation chosen  Strategies for achieving flexibility and portability goals  Limited performance methods restrict evaluation scope  Non-portable methods force use of different techniques  Integration and combination of strategies

6. SC’01 Tutorial Nov. 7, 2001 Multi-Level Instrumentation in TAU

7. SC’01 Tutorial Nov. 7, 2001 Multi-Level Instrumentation  Uses multiple instrumentation interfaces  Shares information: cooperation between interfaces  Taps information at multiple levels  Provides selective instrumentation at each level  Targets a common performance model  Presents a unified view of execution

8. SC’01 Tutorial Nov. 7, 2001 SIMPLE Performance Analysis  SIMPLE hydrodynamics benchmark  C code with MPI message communication  Multiple instrumentation methods  source-to-source translation (PDT)  MPI wrapper library level instrumentation (PMPI)  pre-execution binary instrumentation (DyninstAPI)  Alternative measurement strategies  statistical profiles of software actions  statistical profiles of hardware actions (PCL, PAPI)  program event tracing  choice of time source gettimeofday, high-res physical, CPU, process virtual

9. SC’01 Tutorial Nov. 7, 2001 SIMPLE Source Instrumentation (Preprocessed) int compute_heat_conduction( double theta_hat[X][Y], double deltat, double new_r[X][Y], double new_z[X][Y], double new_alpha[X][Y], double new_rho[X][Y], double theta_l[X][Y], double Gamma_k[X][Y], double Gamma_l[X][Y]) { TAU_PROFILE("int compute_heat_conduction( double (*)[259], double, double (*)[259], double (*)[259], double (*)[259], double (*)[259], double (*)[259], double (*)[259], double (*)[259])", " ", TAU_USER); … }  Similarly, for all other routines in SIMPLE program

10. SC’01 Tutorial Nov. 7, 2001 MPI Library Instrumentation (MPI_Send) int MPI_Send(…) … { int returnVal, typesize; TAU_PROFILE_TIMER(tautimer, "MPI_Send()", " ", TAU_MESSAGE); TAU_PROFILE_START(tautimer); if (dest != MPI_PROC_NULL) { PMPI_Type_size( datatype, &typesize ); TAU_TRACE_SENDMSG(tag, dest, typesize*count); } returnVal = PMPI_Send( buf, count, datatype, dest, tag, comm ); TAU_PROFILE_STOP(tautimer); return returnVal; }

11. SC’01 Tutorial Nov. 7, 2001 MPI Library Instrumentation (MPI_Recv) int MPI_Recv(…) … { int returnVal, size; TAU_PROFILE_TIMER(tautimer, "MPI_Recv()", " ", TAU_MESSAGE); TAU_PROFILE_START(tautimer); returnVal = PMPI_Recv(buf, count, datatype, src, tag, comm, status); if (src != MPI_PROC_NULL && returnVal == MPI_SUCCESS) { PMPI_Get_count( status, MPI_BYTE, &size ); TAU_TRACE_RECVMSG(status->MPI_TAG, status->MPI_SOURCE, size); } TAU_PROFILE_STOP(tautimer); |return returnVal; }

12. SC’01 Tutorial Nov. 7, 2001 four processes profile per process global routine profile Multi-Level Instrumentation (Profiling) SC’01 Tutorial

13. Nov. 7, 2001 Multi-Level Instrumentation (Tracing)  No modification of source instrumentation! TAU performance groups

14. SC’01 Tutorial Nov. 7, 2001 Dynamic Instrumentation of SIMPLE  Uses DynInstAPI for runtime code patching  Mutator loads measurement library, instruments mutatee  one mutator (tau_run) per executable image  mpirun –np tau.shell

15. SC’01 Tutorial Nov. 7, 2001 Multi-Threading Performance Measurement  General issues  Thread identity and per-thread data storage  Performance measurement support and synchronization  Fine-grained parallelism  different forms and levels of threading  greater need for efficient instrumentation  TAU general threading and measurement model  Common thread layer and measurement support  Interface to system specific libraries (reg, id, sync)  Target different thread systems with core functionality  Pthreads, Windows, Java, SMARTS, Tulip, OpenMP

16. SC’01 Tutorial Nov. 7, 2001 Java Multi-Threading Performance (Test Case)  Profile and trace Java (JDK 1.2+) applications  Observe user-level and system-level threads  Observe events for different Java packages  /lang, /io, /awt, …  Test application  SciVis, NPAC, Syracuse University %./configure -jdk= % setenv LD_LIBRARY_PATH $LD_LIBRARY_PATH\: / /lib % java -XrunTAU svserver

17. SC’01 Tutorial Nov. 7, 2001 TAU Profiling of Java Application (SciVis) Profile for each Java thread Captures events for different Java packages 24 threads of execution! global routine profile

18. SC’01 Tutorial Nov. 7, 2001 TAU Tracing of Java Application (SciVis) Performance groups Timeline display Parallelism view

19. SC’01 Tutorial Nov. 7, 2001 Vampir Dynamic Call Tree View (SciVis) Per thread call tree Annotated performance Expanded call tree

20. SC’01 Tutorial Nov. 7, 2001 Virtual Machine Performance Instrumentation  Integrate performance system with VM  Captures robust performance data (e.g., thread events)  Maintain features of environment  portability, concurrency, extensibility, interoperation  Allow use in optimization methods  JVM Profiling Interface (JVMPI)  Generation of JVM events and hooks into JVM  Profiler agent (TAU) loaded as shared object  registers events of interest and address of callback routine  Access to information on dynamically loaded classes  No need to modify Java source, bytecode, or JVM

21. SC’01 Tutorial Nov. 7, 2001 JVMPI Events  Method transition events  Memory events  Heap arena events  Garbage collection events  Class events  Global reference events  Monitor events  Monitor wait events  Thread events  Dump events  Virtual machine events

22. SC’01 Tutorial Nov. 7, 2001 TAU Java JVM Instrumentation Architecture JVMPI Thread API Event notification Java program Profile DB JNI TAU  Robust set of events  Portability  Access to thread info  Measurement options  Limitations  Overhead  Many events  Event control  No user-defined events

23. SC’01 Tutorial Nov. 7, 2001 TAU Java Source Instrumentation Architecture  Any code section can be measured  Portability  Measurement options  Profiling, tracing  Limitations  Source access only  Lack of thread information  Lack of node information Profile database stored in JVM heap TAU as dynamic shared object TAU.Profile class (init, data, output) JNI C bindings Java program TAU package Profile DB JNI TAU

24. SC’01 Tutorial Nov. 7, 2001 Java Source-Level Instrumentation  TAU Java package  User-defined events  TAU.Profile class for new “timers”  Start/Stop  Performance data output at end

25. SC’01 Tutorial Nov. 7, 2001 Mixed-mode Parallel Programs (OpenMPI + MPI)  Portable mixed-mode parallel programming  Multi-threaded shared memory programming  Inter-node message passing  Performance measurement  Access to runtime system and communication events  Associate communication and application events  2-Dimensional Stommel model of ocean circulation  OpenMP for shared memory parallel programming  MPI for cross-box message-based parallelism  Jacobi iteration, 5-point stencil  Timothy Kaiser (San Diego Supercomputing Center)

26. SC’01 Tutorial Nov. 7, 2001 Stommel Instrumentation  Use PMPI for message communication events  OpenMP directive instrumentation (see OPARI in Part 3)

27. SC’01 Tutorial Nov. 7, 2001 OpenMP + MPI Ocean Modeling (Trace) Integrated OpenMP + MPI events Thread message pairing

28. SC’01 Tutorial Nov. 7, 2001 OpenMP + MPI Ocean Modeling (HW Profile) % configure -papi=../packages/papi -openmp -c++=pgCC -cc=pgcc -mpiinc=../packages/mpich/include -mpilib=../packages/mpich/lib FP instructions Integrated OpenMP + MPI events

29. SC’01 Tutorial Nov. 7, 2001 Mixed-mode Parallel Programs (Java + MPI)  Explicit message communication libraries for Java  MPI performance measurement  MPI profiling interface - link-time interposition library  TAU wrappers in native profiling interface library  Send/Receive events and communication statistics  mpiJava (Syracuse, JavaGrande, 1999)  Java wrapper package  JNI C bindings to MPI communication library  Dynamic shared object (libmpijava.so) loaded in JVM  prunjava calls mpirun to distribute program to nodes  Contrast to Java RMI-based schemes (MPJ, CCJ)

30. SC’01 Tutorial Nov. 7, 2001 Native MPI library TAU Java Instrumentation Architecture Java program mpiJava package JNI Profile DB TAU MPI profiling interface TAU wrapper Native MPI library  No source instrumentation  Portability  Measurement options  Limitations  MPI events only  No mpiJava events  Node info only  No thread info TAU package

31. SC’01 Tutorial Nov. 7, 2001 Java Multi-threading and Message Passing  Java threads and MPI communications  Shared-memory multi-threading events  Message communications events  Unified performance measurement and views  Integration of performance mechanisms  Integrated association of performance events  thread event and communication events  user-defined (source-level) performance events  JVM events  Requires instrumentation and measurement cooperation

32. SC’01 Tutorial Nov. 7, 2001 Instrumentation and Measurement Cooperation  Problem  JVMPI doesn’t see MPI events (e.g., rank (node))  MPI profiling interfaces doesn’t see threads  Source instrumentation doesn’t see either!  Need cooperation between interfaces  MPI exposes rank and gets thread information  JVMPI exposes thread information and gets rank  Source instrumentation gets both  Post-mortem matching of sends and receives  Selective instrumentation  java -XrunTAU:exclude=java/io,sun

33. SC’01 Tutorial Nov. 7, 2001 JVMPI Thread API Event notification TAU Java Instrumentation Architecture Java program TAU package mpiJava package MPI profiling interface TAU wrapper Native MPI library Profile DB JNI TAU

34. SC’01 Tutorial Nov. 7, 2001 Parallel Java Game of Life (Profile)  mpiJava testcase  4 nodes, 28 threads Node 0 Node 1 Node 2 Thread 4 executes all MPI routines Merged Java and MPI event profiles

35. SC’01 Tutorial Nov. 7, 2001 Parallel Java Game of Life (Trace)  Integrated event tracing  Merged trace viz  Node process grouping  Thread message pairing  Vampir display  Multi-level event grouping

36. SC’01 Tutorial Nov. 7, 2001 Integrated Performance View (Callgraph)  Source level  MPI level  Java packages level

37. SC’01 Tutorial Nov. 7, 2001 Object-Oriented Programming and C++  Object-oriented programming is based on concepts of abstract data types, encapsulation, inheritance, …  Languages (such as C++) provide support implementing domain-specific abstractions in the form of class libraries  Furthermore, generic programming mechanisms allow for efficient coding abstractions and compile-time transformations  Creates a semantic gap between the transformed code and what the user expects (and describes in source code)  Need a mechanism to expose the nature of high-level abstract computation to the performance tools  Map low-level performance data to high-level semantics

38. SC’01 Tutorial Nov. 7, 2001 C++ Template Instrumentation (Blitz++, PETE)  High-level objects  Array classes  Templates (Blitz++)  Optimizations  Array processing  Expressions ( PETE )  Relate performance data to high-level statement  Complexity of template evaluation Array expressions

39. SC’01 Tutorial Nov. 7, 2001 Standard Template Instrumentation Difficulties  Instantiated templates result in mangled identifiers  Standard profiling techniques / tools are deficient  Integrated with proprietary compilers  Specific systems platforms and programming models Uninterpretable routine names

40. SC’01 Tutorial Nov. 7, 2001 Blitz++ Library Instrumentation  Expression templates embed the form of the expression in a template name  In Blitz++, the library describes the structure of the expression template to the profiling toolkit  Allows for pretty printing the expression templates + B- + 2.0D C BinOp<Add, B, <BinOp<Subtract, C, <BinOp<Multiply, Scalar, D>>> Expression: B + C - 2.0 * D

41. SC’01 Tutorial Nov. 7, 2001 Blitz++ Library Instrumentation (example) 

42. SC’01 Tutorial Nov. 7, 2001 TAU Instrumentation and Profiling for C++ Performance data presented with respect to high-level array expression types Profile of expression types Graphical pprof Racy

43. SC’01 Tutorial Nov. 7, 2001 Hierarchical Parallel Software (C-SAFE/Uintah)  Center for Simulation of Accidental Fires & Explosions  ASCI Level 1 center  PSE for multi-model simulation high-energy explosion  Uintah parallel programming framework  Component-based and object-parallel  Multi-model task-graph scheduling and execution  Shared-memory (thread), distributed-memory (MPI), and mixed-model parallelization  Integrated with SCIRun framework  TAU integration in Uintah  Mapping: task object  grid object  patch object

44. SC’01 Tutorial Nov. 7, 2001 Task Execution in Uintah Parallel Scheduler Task execution time dominates (what task?) MPI communication overheads (where?)

45. SC’01 Tutorial Nov. 7, 2001 Task Computation and Mapping  Task computations on individual particles generate work packets that are scheduled and executed  Work packets that “interpolate particles to grid”  Assign semantic name to a task abstraction  SerialMPM::interpolateParticleToGrid  Partition execution time among different tasks  Need to relate the performance of each particle computation (work packet) to the associated task  Map TAU timer object to task (abstract) computation  Further partition the performance data along different domain-specific axes (task, patches…)  Helps bridge the semantic-gap!

46. SC’01 Tutorial Nov. 7, 2001 Mapping Instrumentation (example) 

47. SC’01 Tutorial Nov. 7, 2001 Work Packet – to – Task Mapping (Profile)

48. SC’01 Tutorial Nov. 7, 2001 Work Packet – to – Task Mapping (Trace) Distinct phases of computation can be identifed based on task See work packet computation events colored by task type

49. SC’01 Tutorial Nov. 7, 2001 Statistics for Relative Task Contributions

50. SC’01 Tutorial Nov. 7, 2001 Comparing Uintah Traces for Scalability Analysis