CentOS 7.0 - man page for papi_num_cmp_hwctrs (centos section 3)
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PAPI_num_cmp_hwctrs(3) PAPI PAPI_num_cmp_hwctrs(3)
Return the number of hardware counters for the specified component.
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
PAPI_library_init() must be called in order for this function to return anything greater
int PAPI_num_cmp_hwctrs(int cidx );
cidx -- An integer identifier for a component. By convention, component 0 is always
the cpu component.
* // Query the cpu component for the number of counters.
On success, this function returns a value greater than zero.
A zero result usually means the library has not been initialized.
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Version 188.8.131.52 Tue Jun 17 2014 PAPI_num_cmp_hwctrs(3)
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