---
name: "pmc_disable"
section: "3"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd"]
url: "https://new.carta.tech/pmc_disable"
---

# pmc\_disable(3)

administrative control of hardware performance counters

## NAME

**pmc\_disable**, **pmc\_enable** – administrative control of hardware performance counters

## LIBRARY

library “libpmc”

## 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

The **pmc\_disable()** function returns the value 0 if successful; 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/3.md), [pmc\_cpuinfo(3)](/pmc_cpuinfo/3.md), [pmc\_pmcinfo(3)](/pmc_pmcinfo/3.md), [hwpmc(4)](/hwpmc/4.md), [pmccontrol(8)](/pmccontrol/8.md), [priv\_check(9)](/priv_check/9.md)