freebsd man page for pmc_enable

PMC_ENABLE(3)						   BSD Library Functions Manual 					     PMC_ENABLE(3)

NAME
     pmc_disable, pmc_enable -- administrative control of hardware performance counters

LIBRARY
     Performance Counters Library (libpmc, -lpmc)

SYNOPSIS
     #include <pmc.h>

     int
     pmc_disable(int cpu, int pmc);

     int
     pmc_enable(int cpu, int pmc);

DESCRIPTION
     These functions allow specific hardware performance monitoring counters in a system to be disabled and enabled administratively.  The hard-
     ware performance counters available on each CPU are numbered using small non-negative integers, in a system dependent manner.  Disabled coun-
     ters will not be available to applications for use.

     The invoking process needs to have the PRIV_PMC_MANAGE privilege to perform these operations.

     Function pmc_disable() disables the hardware counter numbered by argument pmc on CPU number cpu.

     Function pmc_enable() enables the hardware counter numbered by argument pmc on CPU number cpu.

IMPLEMENTATION NOTES
     Hardware PMCs that are currently in use by applications cannot be disabled.  Allocation of a process scope software PMC marks all hardware
     PMCs in the system with the same pmc number as being in-use.

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]		Function pmc_disable() specified a hardware PMC is currently in use.

     [EINVAL]		Arguments cpu or pmc were invalid.

     [ENXIO]		Argument cpu specified a disabled or absent CPU.

     [EPERM]		The current process lacks sufficient privilege to perform this operation.

SEE ALSO
     pmc(3), pmc_cpuinfo(3), pmc_pmcinfo(3), hwpmc(4), pmccontrol(8), priv_check(9)

BSD
								September 22, 2008							       BSD