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.TH "PAPI_num_cmp_hwctrs" 3 "Mon Jun 30 2014" "Version 5.3.2.0" "PAPI" \" -*- nroff -*-
.ad l
.nh
.SH NAME
PAPI_num_cmp_hwctrs \-
.PP
Return the number of hardware counters for the specified component\&.
.SH SYNOPSIS
.br
.PP
.SH "Detailed Description"
.PP
\fBPAPI_num_cmp_hwctrs()\fP returns the number of counters present in the specified component\&. By convention, component 0 is always the cpu\&.
.PP
On some components, especially for CPUs, the value returned is a theoretical maximum for estimation purposes only\&. It might not be possible to easily create an EventSet that contains the full number of events\&. This can be due to a variety of reasons: 1)\&. Some CPUs (especially Intel and POWER) have the notion of fixed counters that can only measure one thing, usually cycles\&. 2)\&. Some CPUs have very explicit rules about which event can run in which counter\&. In this case it might not be possible to add a wanted event even if counters are free\&. 3)\&. Some CPUs halve the number of counters available when running with SMT (multiple CPU threads) enabled\&. 4)\&. Some operating systems 'steal' a counter to use for things such as NMI Watchdog timers\&. The only sure way to see if events will fit is to attempt adding events to an EventSet, and doing something sensible if an error is generated\&.
.PP
\fBPAPI_library_init()\fP must be called in order for this function to return anything greater than 0\&.
.PP
\fBC Interface:\fP
.RS 4
#include <\fBpapi\&.h\fP>
.br
int \fBPAPI_num_cmp_hwctrs(int cidx )\fP;
.RE
.PP
\fBParameters:\fP
.RS 4
\fIcidx\fP -- An integer identifier for a component\&. By convention, component 0 is always the cpu component\&.
.RE
.PP
\fBExample\fP
.RS 4
.PP
.nf
* // Query the cpu component for the number of counters\&.
* printf(\"%d hardware counters found\&.\\n\", PAPI_num_cmp_hwctrs(0));
*
.fi
.PP
.RE
.PP
\fBReturns:\fP
.RS 4
On success, this function returns a value greater than zero\&.
.br
A zero result usually means the library has not been initialized\&.
.RE
.PP
.SH "Author"
.PP
Generated automatically by Doxygen for PAPI from the source code\&.
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