231 lines
6.0 KiB
Groff
231 lines
6.0 KiB
Groff
.\" Copyright (c) 2007-2008 Joseph Koshy. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" This software is provided by Joseph Koshy ``as is'' and
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.\" any express or implied warranties, including, but not limited to, the
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.\" implied warranties of merchantability and fitness for a particular purpose
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.\" are disclaimed. in no event shall Joseph Koshy be liable
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.\" for any direct, indirect, incidental, special, exemplary, or consequential
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.\" damages (including, but not limited to, procurement of substitute goods
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.\" or services; loss of use, data, or profits; or business interruption)
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.\" however caused and on any theory of liability, whether in contract, strict
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.\" liability, or tort (including negligence or otherwise) arising in any way
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.\" out of the use of this software, even if advised of the possibility of
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.\" such damage.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd September 22, 2008
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.Os
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.Dt PMC_CAPABILITIES 3
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.Sh NAME
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.Nm pmc_capabilities ,
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.Nm pmc_cpuinfo ,
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.Nm pmc_ncpu ,
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.Nm pmc_npmc ,
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.Nm pmc_pmcinfo ,
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.Nm pmc_width
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.Nd retrieve information about performance monitoring counters
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.Sh LIBRARY
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.Lb libpmc
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.Sh SYNOPSIS
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.In pmc.h
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.Ft int
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.Fn pmc_capabilities "pmc_id_t pmc" "uint32_t *caps"
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.Ft int
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.Fn pmc_cpuinfo "const struct pmc_cpuinfo **cpu_info"
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.Ft int
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.Fn pmc_ncpu void
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.Ft int
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.Fn pmc_npmc "int cpu"
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.Ft int
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.Fn pmc_pmcinfo "int cpu" "struct pmc_pmcinfo **pmc_info"
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.Ft int
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.Fn pmc_width "pmc_id_t pmc" "uint32_t *width"
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.Sh DESCRIPTION
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These functions retrieve information about performance monitoring
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hardware.
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.Pp
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Function
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.Fn pmc_capabilities
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retrieves the hardware capabilities of a PMC.
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Argument
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.Fa pmc
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is a PMC handle obtained by a prior call to
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.Fn pmc_allocate .
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The function sets argument
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.Fa caps
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to a bitmask of capabilities supported by the PMC denoted by
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argument
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.Fa pmc .
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PMC capabilities are described in
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.Xr pmc 3 .
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.Pp
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Function
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.Fn pmc_cpuinfo
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retrieves information about the CPUs in the system.
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Argument
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.Fa cpu_info
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will be set to point to an internal structure with information about
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the system's CPUs.
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The caller should not free this pointer value.
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This structure has the following fields:
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.Bl -tag -width "pm_classes" -offset indent -compact
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.It pm_cputype
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Specifies the CPU type.
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.It pm_ncpu
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Specifies the number of CPUs in the system.
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.It pm_npmc
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Specifies the number of PMC rows per CPU.
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.It pm_nclass
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Specifies the number of distinct classes of PMCs in the system.
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.It pm_classes
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Contains an array of
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.Vt "struct pmc_classinfo"
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descriptors describing the properties of each class of PMCs
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in the system.
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.El
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.Pp
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Function
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.Fn pmc_ncpu
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is a convenience function that returns the maximum CPU number in
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the system.
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On systems that support sparsely numbered CPUs, not all CPUs may
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be physically present.
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Applications need to be prepared to deal with nonexistent CPUs.
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.Pp
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Function
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.Fn pmc_npmc
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is a convenience function that returns the number of PMCs available
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in the CPU specified by argument
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.Fa cpu .
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.Pp
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Function
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.Fn pmc_pmcinfo
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returns information about the current state of the PMC hardware
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in the CPU specified by argument
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.Fa cpu .
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The location specified by argument
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.Fa pmc_info
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is set to point an array of
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.Vt "struct pmc_info"
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structures each describing the state of one PMC in the CPU.
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These structure contain the following fields:
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.Bl -tag -width pm_ownerpid -offset indent -compact
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.It pm_name
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A human readable name for the PMC.
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.It pm_class
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The PMC class for the PMC.
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.It pm_enabled
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Non-zero if the PMC is enabled.
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.It pm_rowdisp
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The disposition of the PMC row for this PMC.
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Row dispositions are documented in
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.Xr hwpmc 4 .
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.It pm_ownerpid
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If the hardware is in use, the process id of the owner of the PMC.
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.It pm_mode
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The PMC mode as described in
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.Xr pmc 3 .
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.It pm_event
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If the hardware is in use, the PMC event being measured.
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.It pm_flags
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If the hardware is in use, the flags associated with the PMC.
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.It pm_reloadcount
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For sampling PMCs, the reload count associated with the PMC.
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.El
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.Pp
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Function
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.Fn pmc_width
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is used to retrieve the width in bits of the hardware counters
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associated with a PMC.
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Argument
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.Fa pmc
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is a PMC handle obtained by a prior call to
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.Fn pmc_allocate .
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The function sets the location pointed to by argument
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.Fa width
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to the width of the physical counters associated with PMC
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.Fa pmc .
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.Sh RETURN VALUES
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Functions
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.Fn pmc_ncpu
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and
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.Fn pmc_npmc
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returns a positive integer if successful; otherwise the value -1 is
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returned and the global variable
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.Va errno
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is set to indicate the error.
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.Pp
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Functions
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.Fn pmc_capabilities ,
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.Fn pmc_cpuinfo ,
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.Fn pmc_pmcinfo
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and
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.Fn pmc_width
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return 0 if successful; otherwise the value -1 is returned and the
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global variable
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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A call to function
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.Fn pmc_capabilities
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may fail with the following errors:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The argument to the function was invalid.
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.El
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.Pp
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Calls to functions
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.Fn pmc_cpuinfo ,
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.Fn pmc_ncpu
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and
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.Fn pmc_npmc
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may fail with the following errors:
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.Bl -tag -width Er
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.It Bq Er ENXIO
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A prior call to
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.Fn pmc_init
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to initialize the PMC library had failed.
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.El
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.Pp
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A call to function
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.Fn pmc_pmcinfo
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may fail with the following errors:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The argument
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.Fa cpu
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was invalid.
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.It Bq Er ENXIO
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The argument
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.Fa cpu
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specified a disabled or absent CPU.
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.El
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.Pp
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A call to function
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.Fn pmc_width
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may fail with the following errors:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The argument to the function was invalid.
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.El
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.Sh SEE ALSO
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.Xr pmc 3 ,
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.Xr pmc_allocate 3 ,
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.Xr pmc_get_driver_stats 3 ,
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.Xr pmc_name_of_capability 3 ,
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.Xr pmc_name_of_cputype 3 ,
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.Xr pmc_name_of_class 3 ,
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.Xr pmc_name_of_event 3 ,
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.Xr pmc_name_of_mode 3 ,
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.Xr hwpmc 4
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