NAME

       PAPI_num_cmp_hwctrs -

       Return the number of hardware counters for the specified component.

SYNOPSIS

Detailed Description

       PAPI_num_cmp_hwctrs() returns the number of counters present in the specified component.
       By convention, component 0 is always the cpu.

       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.

       PAPI_library_init() must be called in order for this function to return anything greater
       than 0.

       C Interface:
           #include <papi.h>
           int PAPI_num_cmp_hwctrs(int  cidx );

       Parameters:
           cidx -- An integer identifier for a component. By convention, component 0 is always
           the cpu component.

       Example

           // Query the cpu component for the number of counters.
           printf(

       Returns:
           On success, this function returns a value greater than zero.
            A zero result usually means the library has not been initialized.

Author

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