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.TH "PAPI_epc" 3 "Wed Jun 25 2025 19:30:48" "Version 7.2.0.0" "PAPI" \" -*- nroff -*-
.ad l
.nh
.SH NAME
PAPI_epc \- Simplified call to get arbitrary events per cycle, real and processor time\&.
.SH SYNOPSIS
.br
.PP
.SH "Detailed Description"
.PP
.PP
\fBC Interface: \fP
.RS 4
#include <\fBpapi\&.h\fP>
.br
int PAPI_epc( int event, float *rtime, float *ptime, long long *ref, long long *core, long long *evt, float *epc );
.RE
.PP
\fBParameters\fP
.RS 4
\fIevent\fP event code to be measured (0 defaults to PAPI_TOT_INS)
.br
\fI*rtime\fP realtime since the latest call
.br
\fI*ptime\fP process time since the latest call
.br
\fI*ref\fP incremental reference clock cycles since the latest call
.br
\fI*core\fP incremental core clock cycles since the latest call
.br
\fI*evt\fP events since the latest call
.br
\fI*epc\fP incremental events per cycle since the latest call
.RE
.PP
\fBReturn values\fP
.RS 4
\fIPAPI_EINVAL\fP The counters were already started by something other than PAPI_epc()\&.
.br
\fIPAPI_ENOEVNT\fP One of the requested events does not exist\&.
.br
\fIPAPI_ENOMEM\fP Insufficient memory to complete the operation\&.
.RE
.PP
The first call to PAPI_epc() will initialize the PAPI 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\&.
.PP
Subsequent calls will read the counters and return real time, process time, event counts, the core and reference cycle count and EPC rate since the latest call to PAPI_epc()\&.
.PP
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, \fBPAPI_epc\fP provides the information to compute an accurate effective clock rate, and an accurate measure of computational throughput\&. Note that PAPI_epc() is thread-safe and can therefore be called by multiple threads\&.
.PP
\fBSee also\fP
.RS 4
PAPI_flips_rate()
.PP
PAPI_flops_rate()
.PP
PAPI_ipc()
.PP
PAPI_rate_stop()
.RE
.PP
.SH "Author"
.PP
Generated automatically by Doxygen for PAPI from the source code\&.
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