NAME

PAPI_start - Start counting hardware events in an event set.

SYNOPSIS

Detailed Description

C Interface:

#include <papi.h>
int PAPI_start( int EventSet );

Parameters

EventSet -- an integer handle for a PAPI event set as created by PAPI_create_eventset

Return values

PAPI_OK
PAPI_EINVAL -- One or more of the arguments is invalid.
PAPI_ESYS -- A system or C library call failed inside PAPI, see the errno variable.
PAPI_ENOEVST -- The EventSet specified does not exist.
PAPI_EISRUN -- The EventSet is currently counting events.
PAPI_ECNFLCT -- The underlying counter hardware can not count this event and other events in the EventSet simultaneously.
PAPI_ENOEVNT -- The PAPI preset is not available on the underlying hardware.

PAPI_start starts counting all of the hardware events contained in the previously defined EventSet. All counters are implicitly set to zero before counting. Assumes an initialized PAPI library and a properly added event set.

Example:

int EventSet = PAPI_NULL;
long long values[2];
int ret;
ret = PAPI_create_eventset(&EventSet);
if (ret != PAPI_OK) handle_error(ret);
// Add Total Instructions Executed to our EventSet
ret = PAPI_add_event(EventSet, PAPI_TOT_INS);
if (ret != PAPI_OK) handle_error(ret);
// Start counting
ret = PAPI_start(EventSet);
if (ret != PAPI_OK) handle_error(ret);
poorly_tuned_function();
ret = PAPI_stop(EventSet, values);
if (ret != PAPI_OK) handle_error(ret);
printf("%lld\\n",values[0]);

See also

PAPI_create_eventset PAPI_add_event PAPI_stop

Author

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