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PMC_ENABLE(3)
PMC_ENABLE(3) FreeBSD Library Functions Manual PMC_ENABLE(3)

NAME

pmc_disable, pmc_enableadministrative 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 hardware performance counters available on each CPU are numbered using small non-negative integers, in a system dependent manner. Disabled counters 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.
September 22, 2008 FreeBSD