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$FreeBSD$
.Dd September 22, 2008 .Dt PMC_ENABLE 3 .Os .Sh NAME .Nm pmc_disable , .Nm pmc_enable .Nd administrative control of hardware performance counters .Sh LIBRARY .Lb libpmc .Sh SYNOPSIS n 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.
p The invoking process needs to have the .Dv PRIV_PMC_MANAGE privilege to perform these operations.
p Function .Fn pmc_disable disables the hardware counter numbered by argument .Fa pmc on CPU number .Fa cpu .
p 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: l -tag -width Er t Bq Er EBUSY Function .Fn pmc_disable specified a hardware PMC is currently in use. t Bq Er EINVAL Arguments .Fa cpu or .Fa pmc were invalid. t Bq Er ENXIO Argument .Fa cpu specified a disabled or absent CPU. t 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