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)

Check Out this Related Man Page

PAPI_start_counters(3)						       PAPI						    PAPI_start_counters(3)

NAME

       PAPI_start_counters -

       Start counting hardware events.

SYNOPSIS

Detailed Description
       @par C Interface:
       int PAPI_start_counters( int *events, int array_len );

       Parameters:
	   *events an array of codes for events such as PAPI_INT_INS or a native event code
	   array_len the number of items in the *events array

       Return values:
	   PAPI_EINVAL One or more of the arguments is invalid.
	   PAPI_EISRUN Counters have already been started, you must call PAPI_stop_counters() before you call this function again.
	   PAPI_ESYS A system or C library call failed inside PAPI, see the errno variable.
	   PAPI_ENOMEM Insufficient memory to complete the operation.
	   PAPI_ECNFLCT The underlying counter hardware cannot count this event and other events in the EventSet simultaneously.
	   PAPI_ENOEVNT The PAPI preset is not available on the underlying hardware.

       PAPI_start_counters() starts counting the events named in the *events array. This function cannot be called if the counters have already
       been started. The user must call PAPI_stop_counters() to stop the events explicitly if he/she wants to call this function again. It is the
       user's responsibility to choose events that can be counted simultaneously by reading the vendor's documentation. The length of the *events
       array should be no longer than the value returned by PAPI_num_counters().

       if( PAPI_start_counters( Events, num_hwcntrs ) != PAPI_OK )
	   handle_error(1);
	*

       See Also:
	   PAPI_stop_counters() PAPI_add_event() PAPI_create_eventset()

Author
       Generated automatically by Doxygen for PAPI from the source code.

Version 5.2.0.0 						  Tue Jun 17 2014					    PAPI_start_counters(3)

Linux and UNIX Man Pages

papi_epc(3) [centos man page]

Check Out this Related Man Page