.TH "PAPI_num_cmp_hwctrs" 3 "Mon Dec 18 2017" "Version 5.6.0.0" "PAPI" \" -*- nroff -*-
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.SH NAME
PAPI_num_cmp_hwctrs \- 
.PP
Return the number of hardware counters for the specified component\&.  

.SH SYNOPSIS
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.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\&.
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\fBC Interface:\fP
.RS 4
#include <\fBpapi\&.h\fP> 
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 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));
* 

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.PP
.RE
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\fBReturns:\fP
.RS 4
On success, this function returns a value greater than zero\&.
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 A zero result usually means the library has not been initialized\&.
.RE
.PP


.SH "Author"
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Generated automatically by Doxygen for PAPI from the source code\&.