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PMC_READ(3)	       FreeBSD Library Functions Manual		   PMC_READ(3)

NAME
     pmc_read, pmc_rw, pmc_write -- read and write hardware performance	coun-
     ters

LIBRARY
     Performance Counters Library (libpmc, -lpmc)

SYNOPSIS
     #include <pmc.h>

     int
     pmc_read(pmc_id_t pmc, pmc_value_t	*value);

     int
     pmc_rw(pmc_id_t pmc, pmc_value_t newvalue,	pmc_value_t *oldvaluep);

     int
     pmc_write(pmc_id_t	pmc, pmc_value_t value);

DESCRIPTION
     These functions read and write the	current	value of a PMC.

     Function pmc_read() will read the current value of	the PMC	specified by
     argument pmc and write it to the location specified by argument value.

     Function pmc_write() will set the current value of	the PMC	specified by
     argument pmc to the value specified by argument value.

     Function pmc_rw() combines	a read and a write into	a single atomic	opera-
     tion.

     For write operations the PMC should be a quiescent	state.

RETURN VALUES
     Upon successful completion, the value 0 is	returned; otherwise the
     value -1 is returned and the global variable errno	is set to indicate the
     error.

ERRORS
     A call to these functions may fail	with the following errors:

     [EBUSY]		A write	operation specified a currently	running	PMC.

     [EINVAL]		Argument pmc specified a PMC not in a readable state.

     [EINVAL]		The PMC	specified by argument pmc was not owned	by the
			current	process.

SEE ALSO
     pmc(3), hwpmc(4)

FreeBSD	11.2		       November	25, 2007		  FreeBSD 11.2

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO

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