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.\" Copyright (c) 2007-2008 Joseph Koshy. All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" This software is provided by Joseph Koshy ``as is'' and
.\" any express or implied warranties, including, but not limited to, the
.\" implied warranties of merchantability and fitness for a particular purpose
.\" are disclaimed. in no event shall Joseph Koshy be liable
.\" for any direct, indirect, incidental, special, exemplary, or consequential
.\" damages (including, but not limited to, procurement of substitute goods
.\" or services; loss of use, data, or profits; or business interruption)
.\" however caused and on any theory of liability, whether in contract, strict
.\" liability, or tort (including negligence or otherwise) arising in any way
.\" out of the use of this software, even if advised of the possibility of
.\" such damage.
.\"
.\" $FreeBSD$
.\"
.Dd September 22, 2008
.Os
.Dt PMC_ENABLE 3
.Sh NAME
.Nm pmc_disable ,
.Nm pmc_enable
.Nd administrative control of hardware performance counters
.Sh LIBRARY
.Lb libpmc
.Sh SYNOPSIS
.In pmc.h
.Ft int
.Fn pmc_disable "int cpu" "int pmc"
.Ft int
.Fn pmc_enable "int cpu" "int pmc"
.Sh 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.
.Pp
The invoking process needs to have the
.Dv PRIV_PMC_MANAGE
privilege to perform these operations.
.Pp
Function
.Fn pmc_disable
disables the hardware counter numbered by argument
.Fa pmc
on CPU number
.Fa cpu .
.Pp
Function
.Fn pmc_enable
enables the hardware counter numbered by argument
.Fa pmc
on CPU number
.Fa cpu .
.Sh 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.
.Sh RETURN VALUES
.Rv -std
.Sh ERRORS
A call to these functions may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EBUSY
Function
.Fn pmc_disable
specified a hardware PMC is currently in use.
.It Bq Er EINVAL
Arguments
.Fa cpu
or
.Fa pmc
were invalid.
.It Bq Er ENXIO
Argument
.Fa cpu
specified a disabled or absent CPU.
.It Bq Er EPERM
The current process lacks sufficient privilege to perform this
operation.
.El
.Sh SEE ALSO
.Xr pmc 3 ,
.Xr pmc_cpuinfo 3 ,
.Xr pmc_pmcinfo 3 ,
.Xr hwpmc 4 ,
.Xr pmccontrol 8 ,
.Xr priv_check 9
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