Allen D. Malony Sameer S. Shende Robert Bell Department of Computer and Information Science Computational Science Institute University of Oregon The TAU Performance System

SC2002 PERC Tutorial, Nov. 17, Overview  Motivation and goals  TAU architecture and toolkit  Instrumentation  Measurement  Analysis  Performance mapping  Application case studies  …  TAU Integration  Work in progress  Conclusions

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Motivation  Tools for performance problem solving  Empirical-based performance optimization process  Versatile performance technology  Portable performance analysis methods characterization Performance Tuning Performance Diagnosis Performance Experimentation Performance Observation hypotheses properties Instrumentation Measurement Analysis Visualization Performance Technology

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Problems  Diverse performance observability requirements  Multiple levels of software and hardware  Different types and detail of performance data  Alternative performance problem solving methods  Multiple targets of software and system application  Demands more robust performance technology  Broad scope of performance observation  Flexible and configurable mechanisms  Technology integration and extension  Cross-platform portability  Open, layered, and modular framework architecture

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Complexity Challenges for Performance Tools  Computing system environment complexity  Observation integration and optimization  Access, accuracy, and granularity constraints  Diverse/specialized observation capabilities/technology  Restricted modes limit performance problem solving  Sophisticated software development environments  Programming paradigms and performance models  Performance data mapping to software abstractions  Uniformity of performance abstraction across platforms  Rich observation capabilities and flexible configuration  Common performance problem solving methods

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, General Problems (Performance Technology) How do we create robust and ubiquitous performance technology for the analysis and tuning of parallel and distributed software and systems in the presence of (evolving) complexity challenges? How do we apply performance technology effectively for the variety and diversity of performance problems that arise in the context of complex parallel and distributed computer systems? 

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Computation Model for Performance Technology  How to address dual performance technology goals?  Robust capabilities + widely available methods  Contend with problems of system diversity  Flexible tool composition/configuration/integration  Approaches  Restrict computation types / performance problems  machines, languages, instrumentation technique, …  limited performance technology coverage and application  Base technology on abstract computation model  general architecture and software execution features  map features/methods to existing complex system types  develop capabilities that can be adapted and optimized

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, General Complex System Computation Model  Node: physically distinct shared memory machine  Message passing node interconnection network  Context: distinct virtual memory space within node  Thread: execution threads (user/system) in context memory Node VM space Context SMP Threads node memory … … Interconnection Network Inter-node message communication * * physical view model view

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Performance System  Tuning and Analysis Utilities  Performance system framework for scalable parallel and distributed high-performance computing  Targets a general complex system computation model  nodes / contexts / threads  Multi-level: system / software / parallelism  Measurement and analysis abstraction  Integrated toolkit for performance instrumentation, measurement, analysis, and visualization  Portable performance profiling and tracing facility  Open software approach with technology integration  University of Oregon, Forschungszentrum Jülich, LANL

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Definitions – Profiling  Profiling  Recording of summary information during execution  execution time, # calls, hardware statistics, …  Reflects performance behavior of program entities  functions, loops, basic blocks  user-defined “semantic” entities  Very good for low-cost performance assessment  Helps to expose performance bottlenecks and hotspots  Implemented through  sampling: periodic OS interrupts or hardware counter traps  instrumentation: direct insertion of measurement code

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Definitions – Tracing  Tracing  Recording of information about significant points (events) during program execution  entering/exiting code region (function, loop, block, …)  thread/process interactions (e.g., send/receive message)  Save information in event record  timestamp  CPU identifier, thread identifier  Event type and event-specific information  Event trace is a time-sequenced stream of event records  Can be used to reconstruct dynamic program behavior  Typically requires code instrumentation

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Performance System Architecture EPILOG Paraver

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Performance Systems Goals  Multi-level performance instrumentation  Multi-language automatic source instrumentation  Flexible and configurable performance measurement  Widely-ported parallel performance profiling system  Computer system architectures and operating systems  Different programming languages and compilers  Support for multiple parallel programming paradigms  Multi-threading, message passing, mixed-mode, hybrid  Support for performance mapping  Support for object-oriented and generic programming  Integration in complex software systems and applications

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, How To Use TAU?  Instrumentation  Application code and libraries  Selective instrumentation  Install, compile, and link with TAU measurement library  % configure; make clean install  Multiple configurations for different measurements options  Does not require change in instrumentation  Selective measurement control  Execute “experiments” produce performance data  Performance data generated at end or during execution  Use analysis tools to look at performance results

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Instrumentation Approach  Support for standard program events  Routines  Classes and templates  Statement-level blocks  Support for user-defined events  Begin/End events (“user-defined timers”)  Atomic events  Selection of event statistics  Support definition of “semantic” entities for mapping  Support for event groups  Instrumentation optimization

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Instrumentation  Flexible instrumentation mechanisms at multiple levels  Source code  manual  automatic C, C++, F77/90 (Program Database Toolkit (PDT)) OpenMP (directive rewriting (Opari))  Object code  pre-instrumented libraries (e.g., MPI using PMPI)  statically-linked and dynamically-linked  fast breakpoints (compiler generated)  Executable code  dynamic instrumentation (pre-execution) (DynInstAPI)  virtual machine instrumentation (e.g., Java using JVMPI)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Multi-Level Instrumentation  Targets common measurement interface  TAU API  Multiple instrumentation interfaces  Simultaneously active  Information sharing between interfaces  Utilizes instrumentation knowledge between levels  Selective instrumentation  Available at each level  Cross-level selection  Targets a common performance model  Presents a unified view of execution  Consistent performance events

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Program Database Toolkit (PDT)  Program code analysis framework  develop source-based tools  High-level interface to source code information  Integrated toolkit for source code parsing, database creation, and database query  Commercial grade front-end parsers  Portable IL analyzer, database format, and access API  Open software approach for tool development  Multiple source languages  Implement automatic performance instrumentation tools  tau_instrumentor

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PDT Architecture and Tools Application / Library C / C++ parser Fortran 77/90 parser C / C++ IL analyzer Fortran 77/90 IL analyzer Program Database Files IL DUCTAPE PDBhtml SILOON CHASM TAU_instr Program documentation Application component glue C++ / F90 interoperability Automatic source instrumentation

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PDT Components  Language front end  Edison Design Group (EDG): C, C++, Java  Mutek Solutions Ltd.: F77, F90  IL Analyzer  Processes intermediate language (IL) tree from front-end  Creates “program database” (PDB) formatted file  DUCTAPE (Bernd Mohr, FZJ/ZAM, Germany)  C++ program Database Utilities and Conversion Tools APplication Environment  Processes and merges PDB files  C++ library to access the PDB for PDT applications

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Instrumentation Control  Selection of which performance events to observe  Could depend on scope, type, level of interest  Could depend on instrumentation overhead  How is selection supported in instrumentation system?  No choice  Include / exclude lists (TAU)  Environment variables  Static vs. dynamic  Controlling the instrumentation of small routines  High relative measurement overhead  Significant intrusion and possible perturbation

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Selective Instrumentation % tau_instrumentor Usage : tau_instrumentor [-o ] [-noinline] [-g groupname] [-i headerfile] [-c|-c++|-fortran] [-f ] For selective instrumentation, use –f option % cat selective.dat # Selective instrumentation: Specify an exclude/include list. BEGIN_EXCLUDE_LIST void quicksort(int *, int, int) void sort_5elements(int *) void interchange(int *, int *) END_EXCLUDE_LIST # If an include list is specified, the routines in the list will be the only # routines that are instrumented. # To specify an include list (a list of routines that will be instrumented) # remove the leading # to uncomment the following lines #BEGIN_INCLUDE_LIST #int main(int, char **) #int select_ #END_INCLUDE_LIST

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Overhead Analysis for Automatic Selection  Analyze the performance data to determine events with high (relative) overhead performance measurements  Create a select list for excluding those events  Rule grammar (used in tau_reduce tool) [GroupName:] Field Operator Number  GroupName indicates rule applies to events in group  Field is a event metric attribute (from profile statistics)  numcalls, numsubs, percent, usec, cumusec, count, totalcount, stdev, usecs/call, counts/call  Operator is one of >, <, or =  Number is any number  Compound rules possible using “&” between simple rules

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Example Rules  #Exclude all events that are members of TAU_USER #and use less than 1000 microseconds TAU_USER:usec < 1000  #Exclude all events that have less than 100 #microseconds and are called only once usec < 1000 & numcalls = 1  #Exclude all events that have less than 1000 usecs per #call OR have a (total inclusive) percent less than 5 usecs/call < 1000 percent < 5  Scientific notation can be used

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Measurement  Performance information  Performance events  High-resolution timer library (real-time / virtual clocks)  General software counter library (user-defined events)  Hardware performance counters  PCL (Performance Counter Library) (ZAM, Germany)  PAPI (Performance API) (UTK, Ptools Consortium)  consistent, portable API  Organization  Node, context, thread levels  Profile groups for collective events (runtime selective)  Performance data mapping between software levels

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Measurement Options  Parallel profiling  Function-level, block-level, statement-level  Supports user-defined events  TAU parallel profile data stored during execution  Hardware counts values  Support for multiple counters  Support for callpath profiling  Tracing  All profile-level events  Inter-process communication events  Timestamp synchronization  Trace merging and format conversion

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Measurement System Configuration  configure [OPTIONS]  {-c++=, -cc= } Specify C++ and C compilers  {-pthread, -sproc, -smarts}Use pthread, SGI sproc, smarts threads  -openmpUse OpenMP threads  -opari= Specify location of Opari OpenMP tool  {-papi,-pcl= Specify location of PAPI or PCL  -pdt= Specify location of PDT  {-mpiinc=, mpilib= }Specify MPI library instrumentation  - TRACE Generate TAU event traces  -PROFILE Generate TAU profiles  -PROFILECALLPATHGenerate Callpath profiles (1-level)  -MULTIPLECOUNTERSUse more than one hardware counter  -CPUTIMEUse usertime+system time  -PAPIWALLCLOCKUse PAPI to access wallclock time  -PAPIVIRTUALUse PAPI for virtual (user) time …

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Measurement API  Initialization and runtime configuration  TAU_PROFILE_INIT(argc, argv); TAU_PROFILE_SET_NODE(myNode); TAU_PROFILE_SET_CONTEXT(myContext); TAU_PROFILE_EXIT(message); TAU_REGISTIER_THREAD();  Function and class methods  TAU_PROFILE(name, type, group);  Template  TAU_TYPE_STRING(variable, type); TAU_PROFILE(name, type, group); CT(variable);  User-defined timing  TAU_PROFILE_TIMER(timer, name, type, group); TAU_PROFILE_START(timer); TAU_PROFILE_STOP(timer);

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Measurement API (continued)  User-defined events  TAU_REGISTER_EVENT(variable, event_name); TAU_EVENT(variable, value); TAU_PROFILE_STMT(statement);  Mapping  TAU_MAPPING(statement, key); TAU_MAPPING_OBJECT(funcIdVar); TAU_MAPPING_LINK(funcIdVar, key);  TAU_MAPPING_PROFILE (funcIdVar); TAU_MAPPING_PROFILE_TIMER(timer, funcIdVar); TAU_MAPPING_PROFILE_START(timer); TAU_MAPPING_PROFILE_STOP(timer);  Reporting  TAU_REPORT_STATISTICS(); TAU_REPORT_THREAD_STATISTICS();

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Grouping Performance Data in TAU  Profile Groups  A group of related routines forms a profile group  Statically defined  TAU_DEFAULT, TAU_USER[1-5], TAU_MESSAGE, TAU_IO, …  Dynamically defined  group name based on string, such as “adlib” or “particles”  runtime lookup in a map to get unique group identifier  uses tau_instrumentor to instrument  Ability to change group names at runtime  Group-based instrumentation and measurement control

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Group Instrumentation Control API  Enabling Profile Groups  TAU_ENABLE_INSTRUMENTATION();  TAU_ENABLE_GROUP(TAU_GROUP);  TAU_ENABLE_GROUP_NAME(“group name”);  TAU_ENABLE_ALL_GROUPS();  Disabling Profile Groups  TAU_DISABLE_INSTRUMENTATION();  TAU_DISABLE_GROUP(TAU_GROUP);  TAU_DISABLE_GROUP_NAME();  TAU_DISABLE_ALL_GROUPS();  Obtaining Profile Group Identifier  Runtime Switching of Profile Groups

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Pre-execution Control  Dynamic groups defined at file scope  Group names and group associations runtime modifiable  Controlling groups at pre-execution time  --profile option % tau_instrumentor app.pdb app.cpp\ –o app.i.cpp –g “particles” % mpirun –np 4 application\ –profile particles+field+mesh+io  Examples:  POOMA (LANL) uses static groups  VTF (Caltech) uses dynamic group in Python-based execution instrumentation control

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Configuring TAU Measurement Library  Profiling with wallclock time (on a quad PIII Linux machine)  % configure -mpiinc=/usr/local/packages/mpich/include -mpilib=/usr/local/packages/mpich/lib -pdt=/usr/pkg/pdtoolkit/ -useropt=-O2 -LINUXTIMERS  Tracing  % configure -mpiinc=/usr/local/packages/mpich/include -mpilib=/usr/local/packages/mpich/lib -pdt=/usr/pkg/pdtoolkit -useropt=-O2 -LINUXTIMERS  Profiling with PAPI  % configure -mpiinc=/usr/local/packages/mpich/include -mpilib=/usr/local/packages/mpich/lib -pdt=/usr/pkg/pdtoolkit/ -useropt=-O2 -papi=/usr/local/packages/papi  % setenv PAPI_EVENT PAPI_FP_INS  % setenv PAPI_EVENT PAPI_L1_DCM

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Compiling with TAU Makefiles  Include TAU Stub Makefile ( /lib) in the user’s Makefile  Variables:  TAU_CXXSpecify the C++ compiler used by TAU  TAU_CC, TAU_F90Specify the C, F90 compilers  TAU_DEFSDefines used by TAU. Add to CFLAGS  TAU_LDFLAGSLinker options. Add to LDFLAGS  TAU_INCLUDEHeader files include path. Add to CFLAGS  TAU_LIBSStatically linked TAU library. Add to LIBS  TAU_SHLIBSDynamically linked TAU library  TAU_MPI_LIBSTAU’s MPI wrapper library for C/C++  TAU_MPI_FLIBSTAU’s MPI wrapper library for F90  TAU_FORTRANLIBSMust be linked in with C++ linker for F90.  TAU_DISABLETAU’s dummy F90 stub library

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Analysis  Parallel profile analysis  Pprof  parallel profiler with text-based display  Racy  graphical interface to pprof (Tcl/Tk)  jRacy  Java implementation of Racy  Trace analysis and visualization  Trace merging and clock adjustment (if necessary)  Trace format conversion (ALOG, SDDF, VTF, Paraver)  Trace visualization using Vampir (Pallas)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Pprof Command  pprof [-c|-b|-m|-t|-e|-i] [-r] [-s] [-n num] [-f file] [-l] [nodes]  -cSort according to number of calls  -bSort according to number of subroutines called  -mSort according to msecs (exclusive time total)  -tSort according to total msecs (inclusive time total)  -eSort according to exclusive time per call  -iSort according to inclusive time per call  -vSort according to standard deviation (exclusive usec)  -rReverse sorting order  -sPrint only summary profile information  -n numPrint only first number of functions  -f fileSpecify full path and filename without node ids  -l nodesList all functions and exit (prints only info about all contexts/threads of given node numbers)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Pprof Output (NAS Parallel Benchmark – LU)  Intel Quad PIII Xeon  F90 + MPICH  Profile - Node - Context - Thread  Events - code - MPI

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, jRacy (NAS Parallel Benchmark – LU) n: node c: context t: thread Global profiles Routine profile across all nodes Event legend Individual profile

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Paraprof Profile Browser

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Paraprof Profile Browser Main Window

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Paraprof Profile Browser Node Window

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Paraprof Profile Browser (Derived Metrics)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Paraprof Profile Browser Routine Window

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU + PAPI (NAS Parallel Benchmark – LU )  Floating point operations  Re-link to alternate library  Can use multiple counter support

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU + Vampir (NAS Parallel Benchmark – LU) Timeline display Callgraph display Parallelism display Communications display

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, tau_reduce Example  tau_reduce implements overhead reduction in TAU  Consider klargest example  Find kth largest element in a N elements  Compare two methods: quicksort, select_kth_largest  Un-instrumented testcase: i = 2324, N =  quicksort: (wall clock) = secs  select_kth_largest: (wall clock) = secs  Total: (PIII/1.2GHz time) = 0.340u 0.020s 0:00.37  Execute with all routines instrumented  Execute with rule-based selective instrumentation usec>1000 & numcalls> & usecs/call 25

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Simple sorting example on one processor NODE 0;CONTEXT 0;THREAD 0: %Time Exclusive Inclusive #Call #Subrs Inclusive Name msec msec usec/call , int main ,223 4, E E+07 1 void quicksort , int kth_largest_qs , int select_kth_largest , void sort_5elements ,435 1, E void interchange void setup int ceil Before selective instrumentation reduction NODE 0;CONTEXT 0;THREAD 0: %Time Exclusive Inclusive #Call #Subrs Inclusive Name msec total msec usec/call int main int kth_largest_qs int select_kth_largest void setup int ceil After selective instrumentation reduction

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Performance System Status  Computing platforms  IBM SP / Power4, SGI Origin 2K/3K, ASCI Red, Cray T3E / SV-1 (X-1 planned), HP (Compaq) SC (Tru64), HP Superdome (HP-UX), Sun, Hitachi SR8000, NEX SX-5 (SX-6 underway), Linux clusters (IA-32/64, Alpha, PPC, PA-RISC, Power), Apple (OS X), Windows  Programming languages  C, C++, Fortran 77, F90, HPF, Java, OpenMP, Python  Communication libraries  MPI, PVM, Nexus, shmem, Tulip, ACLMPL, MPIJava  Thread libraries  pthreads, SGI sproc, Java,Windows, OpenMP, SMARTS

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Performance System Status (continued)  Compilers  Intel KAI (KCC, KAP/Pro), PGI, GNU, Fujitsu, Sun, Microsoft, SGI, Cray, IBM, Compaq, Hitachi, NEC, Intel  Application libraries (selected)  Blitz++, A++/P++, PETSc, SAMRAI, Overture, PAWS  Application frameworks (selected)  POOMA, MC++, Conejo, Uintah, VTF, UPS, GrACE  Performance projects using TAU  Aurora / SCALEA: ACPC, University of Vienna  TAU full distribution (Version 2.12, web download)  TAU performance system toolkit and user’s guide  Automatic software installation and examples

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PDT Status  Program Database Toolkit (Version 2.2, web download)  EDG C++ front end (Version )  Mutek Fortran 90 front end (Version 2.4.1)  C++ and Fortran 90 IL Analyzer  DUCTAPE library  Standard C++ system header files (KCC Version 4.0f)  PDT-constructed tools  TAU instrumentor (C/C++/F90)  Program analysis support for SILOON and CHASM  Platforms  Same as for TAU with a few exceptions

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Performance Mapping  High-level semantic abstractions  Associate performance measurements  Performance mapping  performance measurement system support to assign data correctly

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17,  New dynamic mapping scheme (SEAA)  Contrast with ParaMap (Miller and Irvin)  Entities defined at any level of abstraction  Attribute entity with semantic information  Entity-to-entity associations  Two association types (implemented in TAU API)  Embedded – extends associated object to store performance measurement entity  External – creates an external look-up table using address of object as key to locate performance measurement entity Semantic Entities/Attributes/Associations …

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Hypothetical Mapping Example  Particles distributed on surfaces of a cube Particle* P[MAX]; /* Array of particles */ int GenerateParticles() { /* distribute particles over all faces of the cube */ for (int face=0, last=0; face < 6; face++){ /* particles on this face */ int particles_on_this_face = num(face); for (int i=last; i < particles_on_this_face; i++) { /* particle properties are a function of face */ P[i] =... f(face);... } last+= particles_on_this_face; }

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Hypothetical Mapping Example (continued)  How much time is spent processing face i particles?  What is the distribution of performance among faces? int ProcessParticle(Particle *p) { /* perform some computation on p */ } int main() { GenerateParticles(); /* create a list of particles */ for (int i = 0; i < N; i++) /* iterates over the list */ ProcessParticle(P[i]); } … engine work packets

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, No Performance Mapping versus Mapping  Typical performance tools report performance with respect to routines  Does not provide support for mapping  Performance tools with SEAA mapping can observe performance with respect to scientist’s programming and problem abstractions TAU (no mapping) TAU (w/ mapping)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Performance Mapping in Callpath Profiling  Consider callgraph (callpath) profiling  Measure time (metric) along an edge (path) of callgraph  Incident edge gives parent / child view  Edge sequence (path) gives parent / descendant view  Callpath profiling when callgraph is unknown  Must determine callgraph dynamically at runtime  Map performance measurement to dynamic call path state  Callpath levels  0-level: current callgraph node  1-level: immediate parent (descendant)  k-level: kth calling parent (call descendant)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Level Callpath Implementation in TAU  TAU maintains a performance event (routine) callstack  Profiled routine (child) looks in callstack for parent  Previous profiled performance event is the parent  A callpath profile structure created first time parent calls  TAU records parent in a callgraph map for child  String representing 1-level callpath used as its key  “a( )=>b( )” : name for time spent in “b” when called by “a”  Map returns pointer to callpath profile structure  1-level callpath is profiled using this profiling data  Build upon TAU’s performance mapping technology  Measurement is independent of instrumentation  Use –PROFILECALLPATH to configure TAU

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Callpath Profiling Example (NAS LU v2.3) % configure -PROFILECALLPATH -SGITIMERS -arch=sgi64 -mpiinc=/usr/include -mpilib=/usr/lib64 -useropt=-O2

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Callpath Parallel Profile Display  0-level and 1-level callpath grouping 1-Level Callpath0-Level Callpath

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, 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

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Case Study: 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

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17,  PDT automatically generates instrumentation code  names events with full function signatures  Similarly for all other routines in SIMPLE program 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);... }

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, 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; } MPI Library Instrumentation (MPI_Send)  Uses MPI profiling interposition library (PMPI)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, 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; }

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Multi-Level Instrumentation (Profiling) four processes Profile per process global profile event legend

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Multi-Level Instrumentation (Tracing)  Relink with TAU library configured for tracing  No modification of source instrumentation required! TAU performance groups

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, 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

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Case Study: PETSc v2.1.3 (ANL)  Portable, Extensible Toolkit for Scientific Computation  Scalable (parallel) PDE framework  Suite of data structures and routines (374,458 code lines)  Solution of scientific applications modeled by PDEs  Parallel implementation  MPI used for inter-process communication  TAU instrumentation  PDT for C/C++ source instrumentation (100%, no manual)  MPI wrapper interposition library instrumentation  Example  Linear system of equations (Ax=b) (SLES) (ex2 test case)  Non-linear system of equations (SNES) (ex19 test case)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex2 (Profile - wallclock time) Sorted with respect to exclusive time

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex2(Profile - overall and message counts)  Observe load balance  Track messages Capture with user- defined events

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex2 (Profile - percentages and time)  View per thread performance on individual routines

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex2 (Trace)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex19  Non-linear solver (SNES)  2-D driven cavity code  Uses velocity-vorticity formulation  Finite difference discretization on a structured grid  Problem size and measurements  56x56 mesh size on quad Pentium III (550 Mhz, Linux)  Executes for approximately one minute  MPI wrapper interposition library  PDT (tau_instrumentor)  Selective instrumentation (tau_reduce)  three routines identified with high instrumentation overhead

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex19 (Profile - wallclock time) Sorted by inclusive time Sorted by exclusive time

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex19 (Profile - overall and percentages)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex19 (Tracing) Commonly seen communicaton behavior

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex19 (Tracing - callgraph)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, PETSc ex19 (PAPI_FP_INS, PAPI_L1_DCM) PAPI_FP_INS PAPI_L1_DCM  Uses multiple counter profile measurement

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Case Study: Mixed-mode Parallel Programs  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)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Stommel Instrumentation  OpenMP directive instrumentation (uses OPARI) pomp_for_enter(&omp_rd_2); #line 252 "stommel.c" #pragma omp for schedule(static) reduction(+: diff) private(j) firstprivate (a1,a2,a3,a4,a5) nowait for( i=i1;i<=i2;i++) { for(j=j1;j<=j2;j++){ new_psi[i][j]=a1*psi[i+1][j] + a2*psi[i-1][j] + a3*psi[i][j+1] + a4*psi[i][j-1] - a5*the_for[i][j]; diff=diff+fabs(new_psi[i][j]-psi[i][j]); } pomp_barrier_enter(&omp_rd_2); #pragma omp barrier pomp_barrier_exit(&omp_rd_2); pomp_for_exit(&omp_rd_2); #line 261 "stommel.c"

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, OpenMP + MPI Ocean Modeling (Trace) Thread-paired message passing Integrated OpenMP + MPI events

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, OpenMP + MPI Ocean Modeling (HW Profile) % configure -papi=../packages/papi -openmp -c++=pgCC -cc=pgcc -mpiinc=../packages/mpich/include -mpilib=../packages/mpich/lib Integrated OpenMP + MPI events FP instructions Integrated OpenMP + MPI events

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Case Study: C++ and Performance Mapping  Object-oriented programming  abstract data types, encapsulation, inheritance, …  Domain-specific abstractions  Implemented by OO languages in form of class libraries  Generic programming mechanisms  efficient coding abstractions, compile-time transformations  Creates a semantic gap between the transformed code and what the user expects (as 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

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, 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 Array expressions

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, 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 Very long! Uninterpretable routine names

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Blitz++ Library Instrumentation  Expression templates  embed the form of the expression in a template name  Blitz++ describes structure of the expression template  Present as pretty printed name to the profiling toolkit  Create performance event associated with expression type + B D C BinOp<Add, B, <BinOp<Subtract, C, <BinOp<Multiply, Scalar, D>>> Expression: B + C * D

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Blitz++ Library Instrumentation (example) #ifdef BZ_TAU_PROFILING static string exprDescription; if (!exprDescription.length()) { exprDescription = "A"; prettyPrintFormat format(_bz_true); // terse mode on format.nextArrayOperandSymbol(); T_update::prettyPrint(exprDescription); expr.prettyPrint(exprDescription, format); } TAU_PROFILE(" ", exprDescription, TAU_BLITZ); #endif exprDescription is the event name

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Instrumentation and Profiling for C++ Performance data presented with respect to high-level array expression types Profile of expression types Performance data presented with respect to high-level array expression types

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Case Study: C-SAFE / Uintah  Center for Simulation of Accidental Fires & Explosions  ASCI ASAP Level 1 center, University of Utah  PSE for multi-model simulation high-energy explosion  Coupled non-linear solvers, optimization, computational steering, visualization, and experimental data verification  Very large-scale simulations  Computer science problems:  Coupling of multiple simulation codes  Software engineering across diverse expert teams  Achieving high performance on large-scale systems

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Example C-SAFE Simulation Problems ∑ Heptane fire simulation Material stress simulation Typical C-SAFE simulation with a billion degrees of freedom and non-linear time dynamics

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Uintah Computational Framework (UCF)  Execution model based on software (macro) dataflow  Exposes parallelism and hides data transport latency  Computations expressed a directed acyclic graphs of tasks  consumes input and produces output (input to future task)  input/outputs specified for each patch in a structured grid  Abstraction of global single-assignment memory  DataWarehouse  Directory mapping names to values (array structured)  Write value once then communicate to awaiting tasks  Task graph gets mapped to processing resources  Communications schedule approximates global optimal

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Performance Technology Integration  Uintah present challenges to performance integration  Software diversity and structure  UCF middleware, simulation code modules  component-based hierarchy  Portability objectives  cross-language and cross-platform  multi-parallelism: thread, message passing, mixed  Scalability objectives  High-level programming and execution abstractions  Requires flexible and robust performance technology  Requires support for performance mapping

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Task Execution in Uintah Parallel Scheduler  Profile methods and functions in scheduler and in MPI library  Need to map performance data! Task execution time dominates (what task?) MPI communication overheads (where?) Task execution time distribution

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Uintah Task Performance Mapping  Uintah partitions individual particles across processing elements (processes or threads)  Simulation tasks in task graph work on particles  Tasks have domain-specific character in the computation  “interpolate particles to grid” in Material Point Method  Task instances generated for each partitioned particle set  Execution scheduled with respect to task dependencies  How to attributed execution time among different tasks  Assign semantic name (task type) to a task instance  SerialMPM::interpolateParticleToGrid  Map TAU timer object to (abstract) task (semantic entity)  Look up timer object using task type (semantic attribute)  Further partition along different domain-specific axes

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Mapping Instrumentation in UCF (example)  Use TAU performance mapping API void MPIScheduler::execute(const ProcessorGroup * pc, DataWarehouseP & old_dw, DataWarehouseP & dw ) {... TAU_MAPPING_CREATE( task->getName(), "[MPIScheduler::execute()]", (TauGroup_t)(void*)task->getName(), task->getName(), 0);... TAU_MAPPING_OBJECT(tautimer) TAU_MAPPING_LINK(tautimer,(TauGroup_t)(void*)task->getName()); // EXTERNAL ASSOCIATION... TAU_MAPPING_PROFILE_TIMER(doitprofiler, tautimer, 0) TAU_MAPPING_PROFILE_START(doitprofiler,0); task->doit(pc); TAU_MAPPING_PROFILE_STOP(0);... }

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Task Performance Mapping (Profile) Mapped task performance across processes Performance mapping for different tasks

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Work Packet – to – Task Mapping (Trace) Work packet computation events colored by task type Distinct phases of computation can be identifed based on task

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Comparing Uintah Traces for Scalability Analysis 8 processes 32 processes

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Online Performance Analysis for C-SAFE Apps Application Performance Steering Performance Visualizer Performance Analyzer Performance Data Reader TAU Performance System Performance Data Integrator SCIRun (Univ. of Utah) // performance data streams // performance data output file system sample sequencing reader synchronization accumulated samples

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, D Field Performance Visualization in SCIRun SCIRun program

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Uintah Computational Framework (UCF)  UCF analysis  Scheduling  MPI library  Components  500 processes  Online and offline visualization  Performance steering  use SCIRun support

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Case Study: SAMRAI (LLNL)  Structured Adaptive Mesh Refinement Application Infrastructure (SAMRAI)  Programming  C++ and MPI  SPMD  Instrumentation  PDT for automatic instrumentation of routines  MPI interposition wrappers  SAMRAI timers for interesting code segments  timers classified in groups (apps, mesh, …)  timer groups are managed by TAU groups

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, SAMRAI (Profile)  Euler (2D) return type routine name

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, SAMRAI Euler (Profile)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, SAMRAI Euler (Trace)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Case Study: EVH1  Enhanced Virginia Hydrodynamics #1 (EVH1)  "TeraScale Simulations of Neutrino-Driven Supernovae and Their Nucleosynthesis" SciDAC project  Configured to run a simulation of the Sedov-Taylor blast wave solution in 2D spherical geometry  Performance study found EVH1 communication bound for more than 64 processors  Predominant routine (>50% of execution time) at this scale is MPI_ALLTOALL  Used in matrix transpose-like operations

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, EVH1 Execution Profile

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, EVH1 Execution Trace MPI_Alltoall is an execution bottleneck

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, TAU Integration (Selected)  SAMRAI (LLNL)  Overture (LLNL)  C-SAFE (ASCI ASAP)  VTF (ASCI ASAP)  SAGE (ASCI LANL)  POOMA, POOMA-II (LANL, Code Sourcery)  PETSc (ANL)  CCA (DOE SciDAC)  GrACE (Rutgers)  Aurora / SCALEA (University of Vienna)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Work in Progress  Trace visualization  Event traces with counters (Vampir 3.0 will visualize)  EPILOG trace conversion  Runtime performance monitoring and analysis  Online performance data access  Performance analysis and visualization in SCIRun  Performance Database Framework  XML parallel profile representation of TAU profiles  PostgresSQL performance database  Next-generation PDT  Performance analysis for component software (CCA)

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Concluding Remarks  Complex software and parallel computing systems pose challenging performance analysis problems that require robust methodologies and tools  To build more sophisticated performance tools, existing proven performance technology must be utilized  Performance tools must be integrated with software and systems models and technology  Performance engineered software  Function consistently and coherently in software and system environments  TAU performance system offers robust performance technology that can be broadly integrated … so USE IT!

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Acknowledgements  Department of Energy (DOE)  MICS office  DOE 2000 ACTS contract  “Performance Technology for Tera-class Parallel Computer Systems: Evolution of the TAU Performance System”  PERC SciDAC project affiliate  University of Utah DOE ASCI Level 1 sub-contract  DOE ASCI Level 3 (LANL, LLNL)  NSF National Young Investigator (NYI) award  Research Centre Juelich  John von Neumann Institute for Computing  Dr. Bernd Mohr  Los Alamos National Laboratory

The TAU Performance SystemSC2002 PERC Tutorial, Nov. 17, Information  TAU (  PDT (  PAPI (  OPARI (