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1.2.1 (revision 3238)
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This is a short example of how to use the OTF2 writing interface.
First include the OTF2 header.
#include <otf2/otf2.h>
For this example an additional include statement is necessary.
#include <stdlib.h>
Furthermore this example uses a function delivering dummy timestamps. Real world applications will use a timer like gettimeofday.
OTF2_TimeStamp get_time( void ) { static uint64_t sequence; return sequence++; }
Define a pre and post flush callback. If no memory is left in OTF2's internal memory buffer or the writer handle is closed a memory buffer flushing routine is triggered. The pre flush callback is triggered right before a buffer flush. It needs to return either OTF2_FLUSH to flush the recorded data to a file or OTF2_NO_FLUSH to supress flushing data to a file. The post flush callback is triggered right after a memory buffer flush. It has to return a current timestamp which is recorded to mark the time spend in a buffer flush.
OTF2_FlushType pre_flush( void* userData, OTF2_FileType fileType, OTF2_LocationRef location, void* callerData, bool final ) { return OTF2_FLUSH; } OTF2_TimeStamp post_flush( void* userData, OTF2_FileType fileType, OTF2_LocationRef location ) { return get_time(); } OTF2_FlushCallbacks flush_callbacks = { .otf2_pre_flush = pre_flush, .otf2_post_flush = post_flush };
int main( int argc, char** argv ) {
Create new archive handle.
OTF2_Archive* archive = OTF2_Archive_Open( "ArchivePath", "ArchiveName", OTF2_FILEMODE_WRITE, 1024 * 1024, 4 * 1024 * 1024, OTF2_SUBSTRATE_POSIX, OTF2_COMPRESSION_NONE );
Set the flush callbacks.
OTF2_Archive_SetFlushCallbacks( archive, &flush_callbacks, NULL );
Define archive as master.
OTF2_Archive_SetMasterSlaveMode( archive, OTF2_MASTER );
Get a local event writer and a local definition writer for location 0. Additionally a global definition writer is needed.
OTF2_EvtWriter* evt_writer = OTF2_Archive_GetEvtWriter( archive, 0 ); OTF2_DefWriter* def_writer = OTF2_Archive_GetDefWriter( archive, 0 ); OTF2_GlobalDefWriter* global_def_writer = OTF2_Archive_GetGlobalDefWriter( archive );
Write an enter and a leave record for region 23 to the local event writer.
OTF2_EvtWriter_Enter( evt_writer, NULL, get_time(), 23 ); OTF2_EvtWriter_Leave( evt_writer, NULL, get_time(), 23 );
Write definitions for the strings as the first records to the global definition writer.
OTF2_GlobalDefWriter_WriteString( global_def_writer, 0, "" ); OTF2_GlobalDefWriter_WriteString( global_def_writer, 1, "Master Process" ); OTF2_GlobalDefWriter_WriteString( global_def_writer, 2, "Main Thread" ); OTF2_GlobalDefWriter_WriteString( global_def_writer, 3, "MyFunction" ); OTF2_GlobalDefWriter_WriteString( global_def_writer, 4, "Alternative function name (e.g. mangled one)" ); OTF2_GlobalDefWriter_WriteString( global_def_writer, 5, "Computes something" ); OTF2_GlobalDefWriter_WriteString( global_def_writer, 6, "MyHost" ); OTF2_GlobalDefWriter_WriteString( global_def_writer, 7, "node" );
Write definition for the code region which was just entered and left to the global definition writer.
OTF2_GlobalDefWriter_WriteRegion( global_def_writer, 23, 3, 4, 5, OTF2_REGION_ROLE_FUNCTION, OTF2_PARADIGM_USER, OTF2_REGION_FLAG_NONE, 0, 0, 0 );
Write the system tree including a definition for the location group to the global definition writer.
OTF2_GlobalDefWriter_WriteSystemTreeNode( global_def_writer, 0, 6, 7, OTF2_UNDEFINED_SYSTEM_TREE_NODE ); OTF2_GlobalDefWriter_WriteLocationGroup( global_def_writer, 0, 1, OTF2_LOCATION_GROUP_TYPE_PROCESS, 0 );
Write a definition for the location to the global definition writer.
OTF2_GlobalDefWriter_WriteLocation( global_def_writer, 0, 2, OTF2_LOCATION_TYPE_CPU_THREAD, 2, 0 );
At the end, close the archive and exit. All opened event and definition writers are closed automatically and the according files are created.
OTF2_Archive_Close( archive ); return EXIT_SUCCESS; }
To compile your program use a command like:
gcc `otf2-config --cflags` -c otf2_writer_example.c -o otf2_writer_example.o
Now you can link your program with:
gcc otf2_writer_example.o `otf2-config --ldflags` `otf2-config --libs` -o otf2_writer_example