Intel® Trace Analyzer and Collector User and Reference Guide

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ID 767272
Date 10/31/2024
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Document Table of Contents
Document Table of Contents x
Intel® Trace Analyzer and Collector User and Reference Guide
Intel® Trace Analyzer and Collector User and Reference Guide x
Introduction Install and Set Up Intel® Trace Analyzer and Collector Trace Your Applications Analyze Your Applications Intel® Trace Collector Reference Intel® Trace Analyzer Reference Notices and Disclaimers
Introduction x
Notational Conventions Get Help
Trace Your Applications x
Tracing Conventional MPI Applications Tracing Failing MPI Applications Usage Instructions How it Works Possible Failures Tracing OpenSHMEM* Applications Tracing MPI File IO Handling of Communicator Names Tracing MPI Load Imbalance Tracing User Defined Events Configuring the Collector Filtering Trace Data Recording OpenMP* Regions Information Tracing System Calls (Linux* OS) Collecting Lightweight Statistics Recording Source Location Information Recording Hardware Performance Information (Linux* OS) Recording Operating System Counters Tracing Library Calls Correctness Checking Tracing Distributed Non-MPI Applications
Correctness Checking x
Correctness Checking of MPI Applications Running with Valgrind* (Linux* OS) Configuring Error Checks Analyzing the Results Debugger Integration
Debugger Integration x
TotalView* Debugger GNU* Symbolic Debugger Allinea* Distributed Debugging Tool* (DDT*)
Analyze Your Applications x
Starting Intel® Trace Analyzer Intel Trace Analyzer Graphical User Interface Navigating Timelines Concepts Viewing Correctness Checking Reports Comparing Two Trace Files Interoperability with Intel® VTune™ Profiler and Intel® Advisor OpenMP* Regions Display Support OTF2 Format Support
Navigating Timelines x
Zoom Stack
Concepts x
Level of Detail Aggregation Advanced Aggregation Tagging and Filtering
Viewing Correctness Checking Reports x
Event Timeline Correctness Checking Reports Qualitative Timeline Correctness Checking Reports Detailed Dialog
Comparing Two Trace Files x
Mappings in Comparison Views Comparison Charts
Mappings in Comparison Views x
Mapping of Processes Mapping of Functions
Comparison Charts x
Comparison Function Profile Comparison Message Profile Comparison Collective Operations Profile
Intel® Trace Collector Reference x
API Reference Configuration Reference Correctness Checking Errors Structured Tracefile Format stftool Utility Time Stamping Secure Loading of Dynamic Link Libraries* on Windows* OS
API Reference x
Initialization, Termination and Control Defining and Recording Source Locations Defining and Recording Functions or Regions Defining and Recording Scopes Defining Groups of Processes Defining and Recording Counters Recording Communication Events Additional API Calls in libVTcs C++ API
Initialization, Termination and Control x
VT_initialize VT_finalize VT_getrank VT_registerthread VT_registernamed VT_registerprefixed VT_getthrank VT_traceon VT_traceoff VT_tracestate VT_symstate VT_flush VT_timestamp VT_timestart VT_setfinalizecallback VT_getdescription VT_countsetcallback
Defining and Recording Functions or Regions x
New Interface Old Interface State Changes
C++ API x
VT_FuncDef Class Reference VT_SclDef Class Reference VT_Function Class Reference VT_Region Class Reference
Configuration Reference x
Configuration File Format Protocol File Configuration Options
Configuration Options x
ACTIVITY ALTSTACK AUTOFLUSH CHECK CHECK-LEAK-REPORT-SIZE CHECK-MAX-DATATYPES CHECK-MAX-ERRORS CHECK-MAX-PENDING CHECK-MAX-REPORTS CHECK-MAX-REQUESTS CHECK-SUPPRESSION-LIMIT CHECK-TIMEOUT CHECK-TRACING CLUSTER COMPRESS-RAW-DATA COUNTER CURRENT-DIR DEADLOCK-TIMEOUT DEADLOCK-WARNING DEMANGLE DETAILED-STATES ENTER-USERCODE ENVIRONMENT EXTENDED-VTF FLUSH-PID FLUSH-PREFIX GROUP HANDLE-SIGNALS INTERNAL-MPI KEEP-RAW-EVENTS LOGFILE-FORMAT LOGFILE-NAME LOGFILE-PREFIX LOGFILE-RANK MEM-BLOCKSIZE MEM-FLUSHBLOCKS MEM-INFO MEM-MAXBLOCKS MEM-MINBLOCKS MEM-OVERWRITE NMCMD OS-COUNTER-DELAY PCTRACE PCTRACE-CACHE PCTRACE-FAST PLUGIN PROCESS PROGNAME PROTOFILE-NAME STATISTICS STATE STF-PROCS-PER-FILE STF-USE-HW-STRUCTURE STOPFILE-NAME SYMBOL SYNC-MAX-DURATION SYNC-MAX-MESSAGES SYNC-PERIOD SYNCED-CLUSTER SYNCED-HOST TIME-WINDOWS (Experimental) TIMER TIMER-SKIP UNIFY-COUNTERS UNIFY-GROUPS UNIFY-SCLS UNIFY-SYMBOLS VERBOSE VT_START_PAUSED VT_COMPRESS_TRACE
Correctness Checking Errors x
Supported Errors How the Collection Works
How the Collection Works x
Parameter Checking Premature Exit Overlapping Memory Detecting Illegal Buffer Modifications Buffer Given to MPI Cannot Be Read or Written Distributed Memory Checking Illegal Memory Access Request Handling Datatype Handling Buffered Sends Deadlocks Checking Message Transmission Datatype Mismatches Data Modified during Transmission Checking Collective Operations Freeing Communicators
Structured Tracefile Format x
STF Components Single-File STF Configuring STF
stftool Utility x
stftool Utility Options Expanded ASCII output of STF Files
Time Stamping x
Clock Synchronization Choosing a Timer
Choosing a Timer x
gettimeofday/_ftime QueryPerformanceCounter CPU Cycle Counter Normalized CPU Cycle Counter MPI_Wtime() High Precision Event Timers POSIX* clock_gettime
Intel® Trace Analyzer Reference x
Graphical User Interface Reference Intel® Trace Analyzer Command Line Interface Reference Filter Expression Grammar otf2-to-stf Utility
Graphical User Interface Reference x
Welcome Page Summary Page Main Menu Bar View Menu Bar View Bars Charts Dialogs Settings
Main Menu Bar x
File Menu Options Menu Project Menu  Windows Menu Help Menu
View Menu Bar x
View Charts Navigate Advanced Layout Comparison Menu
Advanced x
Tagging Specific Events Filtering Events Simulating Ideal Communication Checking Application Imbalance Aggregating Results Aggregating Functions Creating Command Line for Intel® VTune™ Profiler and Intel® Advisor
View Bars x
Toolbar Trace Map Status Bar
Charts x
Event Timeline Qualitative Timeline Quantitative Timeline Counter Timeline Function Profile Message Profile Collective Operations Profile Performance Assistant Common Chart Features
Event Timeline x
Context Menu Filtering and Tagging
Qualitative Timeline x
Context Menu Filtering and Tagging
Quantitative Timeline x
Context Menu Filtering and Tagging
Counter Timeline x
Context Menu Filtering and Tagging
Function Profile x
Flat Profile Load Balance Call Tree Call Graph Context Menu Filtering and Tagging Function Profile Settings
Message Profile x
Context Menu Filtering and Tagging Aggregation Message Profile Settings
Collective Operations Profile x
Context Menu Filtering and Tagging Collective Operations Profile Settings
Dialogs x
Process Aggregation Function Aggregation Function Group Color Editor Filtering Dialog Box Tagging Dialog Box Idealization Dialog Box Imbalance Diagram Dialog Box Trace Merge Dialog Box  Details Dialog Box Source View Dialog Time Interval Selection Configuration Dialogs Find Dialog Box Command line for Intel® VTune™ Profiler and Intel® Advisor Dialog Box OTF2 to STF Conversion Dialog Box Configuration Assistant
Process Aggregation x
Comparison Mode
Function Aggregation x
Comparison Mode
Filtering Dialog Box x
Building Filter Expressions Using Graphical Interface Building Filter Expressions Manually Filter Expressions in Comparison Mode
Details Dialog Box x
Detailed Attributes of Function Events Detailed Attributes of Message Events Detailed Attributes of Collective Operation Events
Configuration Dialogs x
Load Configuration File Dialog Edit Configuration File Dialog
Settings x
Preferences Font Settings Number Formatting Settings
Preferences x
General Preferences Tracefile Preferences Event Timeline Settings Qualitative Timeline Settings Quantitative Timeline Settings Counter Timeline Settings
Notices and Disclaimers x
Appendix A Copyright and Licenses
Intel® Trace Analyzer and Collector User and Reference Guide

Tracing Failing MPI Applications

Normally, if an MPI application fails or is aborted, all the trace data collected is lost, because libVT needs a working MPI to write the trace file. However, the user might want to use the data collected up to that point. To solve this problem, Intel® Trace Collector provides the libVTfs library that enables tracing of failing MPI applications.

Usage Instructions

To trace failing MPI applications, do the following:

Linux* OS

Set the LD_PRELOAD environment variable to point to the libVTfs library and run the application. For example: 

$ export LD_PRELOAD=libVTfs.so
$ mpirun -n 4 ./myApp

Alternatively, rebuild your application with the static version of the library. For example: 

$ mpiicc -profile=vtfs myApp.c -o myApp

Windows* OS

Relink your application with the libVTfs library before the Intel MPI Library and run it as usual. To do this, you should create an Intel® MPI Library configuration file that points to the libVTfs library. You can do it as follows (administrator privileges may be required): 

> echo SET PROFILE_PRELIB=%VT_ROOT%\lib\VTfs.lib > %I_MPI_ROOT%\lib\VTfs.conf
> mpiicc -profile=VTfs myApp.c
> mpiexec -n 4 myApp.exe

How it Works

Under normal circumstances tracing works like with libVT, but communication during trace file writing is done through TCP sockets, so it may take more time than over MPI. In order to establish communication, it needs to know the IP addresses of all the hosts involved. It finds them by looking up the hostname locally on each machine or, if that only yields the 127.0.0.1 local host IP address, falls back to broadcasting hostnames. In the latter case hostname lookup must work consistently in the cluster. In case of a failure, libVTfs freezes all MPI processes and then writes a trace file with all trace data.

Possible Failures

Failure Description
Signals

Includes events inside the application like segmentation faults and floating point errors, and also abort signals sent from outside, like SIGINT or SIGTERM.

Only SIGKILL will abort the application without writing a trace because it cannot be caught.

Premature Exit One or more processes exit without calling MPI_Finalize().
MPI Errors MPI detects certain errors itself, like communication problems or invalid parameters for MPI functions.
Deadlocks

If Intel® Trace Collector observes no progress for a certain amount of time in any process, it assumes that a deadlock has occurred, stops the application and writes a trace file.

You can configure the timeout with DEADLOCK-TIMEOUT. "No progress" is defined as "inside the same MPI call". This is only a heuristic and may fail to lead to both false positives and false negatives.

Undetected Deadlock

If the application polls for a message that cannot arrive with MPI_Test() or a similar non-blocking function, Intel® Trace Collector still assumes that progress is made and does not stop the application.

To avoid this, use blocking MPI calls in the application, which is also better for performance.

Premature Abort

If all processes remain in MPI for a long time due to a long data transfer for instance, then the timeout might be reached. Because the default timeout is five minutes, this is very unlikely. After writing the trace libVTfs will try to clean up the MPI application run by sending all processes in the same process group an INT signal. This is necessary because certain versions of MPICH* may have spawned child processes which keep running when an application aborts prematurely, but there is a certain risk that the invoking shell also receives this signal and also terminates. If that happens, then it helps to invoke mpirun inside a remote shell: 

rsh localhost 'sh -c "mpirun . . . "'

MPI errors cannot be ignored by installing an error handler. libVTfs overrides all requests to install one and uses its own handler instead. This handler stops the application and writes a trace without trying to proceed, otherwise it would be impossible to guarantee that any trace will be written at all.

On Windows* OS, not all features of POSIX* signal handling are available. Therefore, VTfs on Windows* OS uses some heuristics and may not work as reliably as on Linux* OS. It is not possible to stop a Windows* application run and get a trace file by sending a signal or terminating the job in the Windows task manager.

Parent topic: Trace Your Applications
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