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papi_epc(3) [centos man page]

PAPI_epc(3)							       PAPI							       PAPI_epc(3)

NAME
PAPI_epc - Simplified call to get arbitrary events per cycle, real and processor time. SYNOPSIS
Detailed Description C Interface: #include <papi.h> int PAPI_epc( int event, float *rtime, float *ptime, long long *ref, long long *core, long long *evt, float *epc ); Parameters: event event code to be measured (0 defaults to PAPI_TOT_INS) *rtime total realtime since the first call *ptime total process time since the first call *ref incremental reference clock cycles since the last call *core incremental core clock cycles since the last call *evt total events since the first call *epc incremental events per cycle since the last call Return values: PAPI_EINVAL The counters were already started by something other than PAPI_epc(). PAPI_ENOEVNT One of the requested events does not exist. PAPI_ENOMEM Insufficient memory to complete the operation. The first call to PAPI_epc() will initialize the PAPI High Level interface, set up the counters to monitor the user specified event, PAPI_TOT_CYC, and PAPI_REF_CYC (if it exists) and start the counters. Subsequent calls will read the counters and return total real time, total process time, total event counts since the start of the measurement and the core and reference cycle count and EPC rate since the latest call to PAPI_epc(). A call to PAPI_stop_counters() will stop the counters from running and then calls such as PAPI_start_counters() or other rate calls can safely be used. PAPI_epc can provide a more detailed look at algorithm efficiency in light of clock variability in modern cpus. MFLOPS is no longer an adequate description of peak performance if clock rates can arbitrarily speed up or slow down. By allowing a user specified event and reporting reference cycles, core cycles and real time, PAPI_epc provides the information to compute an accurate effective clock rate, and an accurate measure of computational throughput. See Also: PAPI_flips() PAPI_flops() PAPI_ipc() PAPI_stop_counters() Author Generated automatically by Doxygen for PAPI from the source code. Version 5.2.0.0 Tue Jun 17 2014 PAPI_epc(3)

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PAPI_read_counters(3)						       PAPI						     PAPI_read_counters(3)

NAME
PAPI_read_counters - Read and reset counters. SYNOPSIS
Detailed Description @par C Interface: int PAPI_read_counters( long long *values, int array_len ); Parameters: *values an array to hold the counter values of the counting events arry_len the number of items in the *events array Precondition: These calls assume an initialized PAPI library and a properly added event set. Postcondition: The counters are reset and left running after the call. Return values: 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_read_counters() copies the event counters into the array *values. do_100events(); if ( PAPI_read_counters( values, num_hwcntrs ) != PAPI_OK ) handlw_error(1); // values[0] now equals 100 do_100events(); if ( PAPI_accum_counters( values, num_hwcntrs ) != PAPI_OK ) handle_error(1); // values[0] now equals 200 values[0] = -100; do_100events(); if ( PAPI_accum_counters(values, num_hwcntrs ) != PAPI_OK ) handle_error(); // values[0] now equals 0 * See Also: PAPI_set_opt() PAPI_start_counters() Fortran Interface: #include 'fpapi.h' PAPIF_read_counters( C_LONG_LONG(*) values, C_INT array_len, C_INT check ) See Also: PAPI_read_counters Author Generated automatically by Doxygen for PAPI from the source code. Version 5.2.0.0 Tue Jun 17 2014 PAPI_read_counters(3)
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