185 lines
5.1 KiB
Groff
185 lines
5.1 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_ALLOCATE 3
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.Sh NAME
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.Nm pmc_allocate ,
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.Nm pmc_release
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.Nd allocate and free 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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.Fo pmc_allocate
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.Fa "const char *eventspecifier"
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.Fa "enum pmc_mode mode"
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.Fa "uint32_t flags"
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.Fa "int cpu"
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.Fa "pmc_id_t *pmcid"
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.Fc
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.Ft int
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.Fn pmc_release "pmc_id_t pmc"
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.Sh DESCRIPTION
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Function
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.Fn pmc_allocate
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allocates a performance monitoring counter that measures the events
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named by argument
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.Fa eventspecifier ,
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and writes the allocated handle to the location pointed to by argument
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.Fa pmcid .
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.Pp
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Argument
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.Fa eventspecifier
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comprises an PMC event name followed by an optional comma separated
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list of keywords and qualifiers.
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The allowed syntax for argument
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.Fa eventspecifier
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is processor specific and is listed in section
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.Sx "EVENT SPECIFIERS"
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in the
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.Xr pmc 3
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manual page.
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.Pp
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The desired PMC mode is specified by argument
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.Fa mode .
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Legal values for the
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.Fa mode
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argument are:
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.Bl -tag -width ".Dv PMC_MODE_SS" -compact
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.It Dv PMC_MODE_SC
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Allocate a system-scope counting PMC.
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.It Dv PMC_MODE_SS
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Allocate a system-scope sampling PMC.
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.It Dv PMC_MODE_TC
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Allocate a process-scope counting PMC.
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.It Dv PMC_MODE_TS
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Allocate a process-scope sampling PMC.
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.El
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.Pp
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Mode specific modifiers may be specified using argument
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.Fa flags .
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The flags supported at PMC allocation time are:
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.Bl -tag -width ".Dv PMC_F_LOG_PROCEXIT" -compact
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.It Dv PMC_F_DESCENDANTS
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For process-scope PMCs, automatically track descendants of attached
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processes.
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.It Dv PMC_F_LOG_PROCCSW
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For process-scope counting PMCs, generate a log event at every context
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switch containing the incremental number of hardware events seen
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by the process during the time it was executing on the CPU.
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.It Dv PMC_F_LOG_PROCEXIT
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For process-scope counting PMCs, accumulate hardware events seen
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when the process was executing on a CPU and generate a log event
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when an attached process exits.
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.El
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PMCs allocated with flags
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.Dv PMC_F_LOG_PROCCSW
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and
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.Dv PMC_F_LOG_PROCEXIT
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need a log file to be configured before they are started.
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.Pp
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For system scope PMCs, the argument
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.Fa cpu
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is a non-negative value that specifies the CPU number
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that the PMC is to be allocated on.
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Process scope PMC allocations should specify the constant
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.Dv PMC_CPU_ANY
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for this argument.
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.Pp
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Function
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.Fn pmc_release
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releases the PMC denoted by argument
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.Fa pmcid .
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.Sh RETURN VALUES
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If successful, function
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.Fn pmc_allocate
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sets the location specified by argument
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.Fa pmcid
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to the handle of the allocated PMC and returns 0.
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In case of an error, the function returns -1 and sets the global
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variable
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.Va errno
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to indicate the error.
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.Pp
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.Rv -std pmc_release
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.Sh 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 mode
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to function
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.Fn pmc_allocate
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had an invalid value.
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.It Bq Er EINVAL
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Argument
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.Fa cpu
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to function
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.Fn pmc_allocate
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had an invalid CPU number.
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.It Bq Er EINVAL
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Argument
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.Fa flags
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contained flags that were unsupported or otherwise incompatible with
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the requested PMC mode.
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.It Bq Er EINVAL
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Argument
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.Fa eventspecifier
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to function
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.Fn pmc_allocate
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specified an event not supported by hardware or contained a syntax
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error.
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.It Bq Er ENXIO
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Function
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.Fn pmc_allocate
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requested the use of a hardware resource that was absent or
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administratively disabled.
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.It Bq Er EOPNOTSUPP
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The underlying hardware does not support the capabilities needed for
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a PMC being allocated by a call to
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.Fn pmc_allocate .
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.It Bq Er EPERM
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A system scope PMC allocation was attempted without adequate process
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privilege.
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.It Bq Er ESRCH
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Function
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.Fn pmc_release
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was called without first having allocated a PMC.
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.It Bq Er EINVAL
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Argument
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.Fa pmcid
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to function
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.Fn pmc_release
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did not specify a PMC previously allocated by this process.
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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_attach 3 ,
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.Xr pmc_configure_logfile 3 ,
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.Xr pmc_start 3 ,
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.Xr hwpmc 4
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