lib/libpmc/pmc_capabilities.3

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.Dd November 24, 2007
.Os
.Dt PMC_CAPABILITIES 3
.Sh NAME
.Nm pmc_capabilities ,
.Nm pmc_cpuinfo ,
.Nm pmc_ncpu ,
.Nm pmc_npmc ,
.Nm pmc_pmcinfo ,
.Nm pmc_width
.Nd retrieve information about performance monitoring counters
.Sh LIBRARY
.Lb libpmc
.Sh SYNOPSIS
.In pmc.h
.Ft int
.Fn pmc_capabilities "pmc_id_t pmc" "uint32_t *caps"
.Ft int
.Fn pmc_cpuinfo "const struct pmc_cpuinfo **cpu_info"
.Ft int
.Fn pmc_ncpu void
.Ft int
.Fn pmc_npmc "int cpu"
.Ft int
.Fn pmc_pmcinfo "int cpu" "struct pmc_pmcinfo **pmc_info"
.Ft int
.Fn pmc_width "pmc_id_t pmc" "uint32_t *width"
.Sh DESCRIPTION
These functions retrieve information about performance monitoring
hardware.
.Pp
Function
.Fn pmc_capabilities
retrieves the hardware capabilities of a PMC.
Argument
.Fa pmc
is a PMC handle obtained by a prior call to
.Fn pmc_allocate .
The function sets argument
.Fa caps
to a bitmask of capabilities supported by the PMC denoted by
argument
.Fa pmc .
PMC capabilities are described in
.Xr pmc 3 .
.Pp
Function
.Fn pmc_cpuinfo
retrieves information about the CPUs in the system.
Argument
.Fa cpu_info
will be set to point to an internal structure with information about
the system's CPUs.
The caller should not free this pointer value.
This structure has the following fields:
.Bl -tag -width "pm_classes" -offset indent -compact
.It pm_cputype
Specifies the CPU type.
.It pm_ncpu
Specifies the number of CPUs in the system.
.It pm_npmc
Specifies the number of PMC rows per CPU.
.It pm_nclass
Specifies the number of distinct classes of PMCs in the system.
.It pm_classes
Contains an array of
.Vt "struct pmc_classinfo"
descriptors describing the properties of each class of PMCs
in the system.
.El
.Pp
Function
.Fn pmc_ncpu
is a convenience function that returns the number of CPUs in the
system.
.Pp
Function
.Fn pmc_npmc
is a convenience function that returns the number of PMCs available
in the CPU specified by argument
.Fa cpu .
.Pp
Function
.Fn pmc_pmcinfo
returns information about the current state of the PMC hardware
in the CPU specified by argument
.Fa cpu .
The location specified by argument
.Fa pmc_info
is set to point an array of
.Vt "struct pmc_info"
structures each describing the state of one PMC in the CPU.
These structure contain the following fields:
.Bl -tag -width pm_ownerpid -offset indent -compact
.It pm_name
A human readable name for the PMC.
.It pm_class
The PMC class for the PMC.
.It pm_enabled
Non-zero if the PMC is enabled.
.It pm_rowdisp
The disposition of the PMC row for this PMC.
Row dispositions are documented in
.Xr hwpmc 4 .
.It pm_ownerpid
If the hardware is in use, the process id of the owner of the PMC.
.It pm_mode
The PMC mode as described in
.Xr pmc 3 .
.It pm_event
If the hardware is in use, the PMC event being measured.
.It pm_flags
If the hardware is in use, the flags associated with the PMC.
.It pm_reloadcount
For sampling PMCs, the reload count associated with the PMC.
.El
.Pp
Function
.Fn pmc_width
is used to retrieve the width in bits of the hardware counters
associated with a PMC.
Argument
.Fa pmc
is a PMC handle obtained by a prior call to
.Fn pmc_allocate .
The function sets the location pointed to by argument
.Fa width
to the width of the physical counters associated with PMC
.Fa pmc .
.Sh RETURN VALUES
Functions
.Fn pmc_ncpu
and
.Fn pmc_npmc
returns a positive integer if successful; otherwise the value -1 is
returned and the global variable
.Va errno
is set to indicate the error.
.Pp
Functions
.Fn pmc_capabilities ,
.Fn pmc_cpuinfo ,
.Fn pmc_pmcinfo
and
.Fn pmc_width
return 0 if successful; otherwise the value -1 is returned and the
global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
A call to function
.Fn pmc_capabilities
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EINVAL
The argument to the function was invalid.
.El
.Pp
Calls to functions
.Fn pmc_cpuinfo ,
.Fn pmc_ncpu
and
.Fn pmc_npmc
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er ENXIO
A prior call to
.Fn pmc_init
to initialize the PMC library had failed.
.El
.Pp
A call to function
.Fn pmc_pmcinfo
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EINVAL
The argument
.Fa cpu
specified a non-existent CPU.
.It Bq Er ENXIO
The argument
.Fa cpu
specified a disabled CPU.
.El
.Pp
A call to function
.Fn pmc_width
may fail with the following errors:
.Bl -tag -width Er
.It Bq Er EINVAL
The argument to the function was invalid.
.El
.Sh SEE ALSO
.Xr pmc 3 ,
.Xr pmc_allocate 3 ,
.Xr pmc_get_driver_stats 3 ,
.Xr pmc_name_of_capability 3 ,
.Xr pmc_name_of_cputype 3 ,
.Xr pmc_name_of_class 3 ,
.Xr pmc_name_of_event 3 ,
.Xr pmc_name_of_mode 3 ,
.Xr hwpmc 4