Microsoft Windows* 8.x

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New Interface

To simplify the use of user-defined states, a new interface has been introduced for Intel® Trace Collector. It manages the symbol handles automatically, freeing the user from the task of assigning and keeping track of symbol handles, and has a reduced number of arguments. Furthermore, the performance of the new functions has been optimized, reducing the overhead of recording state changes.

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Old Interface

To define a new symbol, first determine which value has to be used for the symbol handle, and then call the VT_symdef() function, passing the symbol and activity names, plus the handle value. It is not necessary to define the activity itself. Make sure to not use the same handle value for different symbols.

VT_symdef

int VT_symdef (int statehandle, const char * symname, const char * activity)

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State Changes

The following functions take a state handle defined with either the new or old interface. Handles defined with the old interface incur a higher overhead in these functions, because they need to be mapped to the real internal handles. Therefore it is better to use the new interface.

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Defining and Recording Scopes

Scope is a user-defined region in the source code. In contrast to regions and functions, which are entered and left with VT_begin/VT_end() or VT_enter/VT_leave(), scope does not follow the stack based approach. It is possible to start scope a, then start scope b and stop a before b, that is they can overlap one another:

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Defining Groups of Processes

Intel® Trace Collector enables you to define an arbitrary, recursive group structure over the processes of an MPI application, and Intel® Trace Analyzer can display profiling and communication statistics for these groups. Thus, you can start with the top-level groups and walk down the hierarchy, unfolding interesting groups into ever more detail until you arrive at the level of processes or threads.

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Recording Communication Events

These are API calls that allow logging of message send and receive and MPI-style collective operations. Because they are modeled after MPI operations, they use the same kind of communicator to define the context for the operation.

enum _VT_CommIDs

Logging send/receive events evaluates the rank local within the active communicator, and matches events only if they take place in the same communicator (in other words, it is the same behavior as in MPI).

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Additional API Calls in libVTcs

VT_abort

int VT_abort (void)

Description

Abort a VT_initialize() or VT_finalize() call running concurrently in a different thread.

This call will not block, but it might still take a while before the aborted calls actually return. They will return either successfully (if they have completed without aborting) or with an error code.

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C++ API

These are wrappers around the C API calls which simplify instrumentation of C++ source code and ensure correct tracing if exceptions are used. Because all the member functions are provided as inline functions it is sufficient to include VT.h to use these classes with every C++ compiler.

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