220 lines
5.9 KiB
Groff
220 lines
5.9 KiB
Groff
.\" $NetBSD: pmc_control.2,v 1.3 2003/01/18 11:33:09 thorpej Exp $
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.\"
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.\" Copyright (c) 2002 Wasabi Systems, Inc.
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.\" All rights reserved.
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.\"
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.\" Written by Allen Briggs for Wasabi Systems, Inc.
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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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed for the NetBSD Project by
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.\" Wasabi Systems, Inc.
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.\" 4. The name of Wasabi Systems, Inc. may not be used to endorse
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.\" or promote products derived from this software without specific prior
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.\" written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd July 23, 2002
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.Dt PMC_CONTROL 2
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.Os
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.Sh NAME
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.Nm pmc_control ,
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.Nm pmc_get_info
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.Nd Hardware Performance Monitoring Interface
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.Fd #include \*[Lt]sys/pmc.h\*[Gt]
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.Ft int
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.Fn pmc_control "int ctr" "int op" "void *argp"
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.Ft int
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.Fn pmc_get_info "int ctr" "int op" "void *argp"
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.Sh DESCRIPTION
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.Fn pmc_get_info
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returns the number of counters in the system or information on a specified
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counter
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.Fa ctr .
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The possible values for
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.Fa op
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are:
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.Bl -tag -width width
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.It PMC_INFO_NCOUNTERS
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When querying the number of counters in the system,
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.Fa ctr
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is ignored and
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.Fa argp
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is of type
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.Em int * .
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Upon return, the integer pointed to by
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.Fa argp
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will contain the number of counters that are available in the system.
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.It PMC_INFO_COUNTER_VALUE
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When querying the value of a counter in the system,
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.Fa ctr
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refers to the counter being queried, and
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.Fa argp
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is of type
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.Em uint64_t * .
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Upon return, the 64-bit integer pointed to by
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.Fa argp
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will contain the value of the specified counter.
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.It PMC_INFO_ACCUMULATED_COUNTER_VALUE
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When querying the value of a counter in the system,
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.Fa ctr
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refers to the counter being queried, and
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.Fa argp
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is of type
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.Em uint64_t * .
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Upon return, the 64-bit integer pointed to by
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.Fa argp
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will contain the sum of the accumulated values of specified counter in
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all exited subprocesses of the current process.
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.El
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.Pp
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.Fn pmc_control
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manipulates the specified counter
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.Fa ctr
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in one of several fashions.
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The
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.Fa op
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parameter determines the action taken by the kernel and also the interpretation of the
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.Fa argp
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parameter.
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The possible values for
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.Fa op
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are:
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.Bl -tag -width width
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.It PMC_OP_START
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Starts the specified
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.Fa ctr
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running.
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It must be preceded by a call with
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.Em PMC_OP_CONFIGURE .
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.Fa argp
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is ignored in this case and may be
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.Dv NULL .
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.It PMC_OP_STOP
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Stops the specified
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.Fa ctr
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from running.
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.Fa argp
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is ignored in this case and may be
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.Dv NULL .
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.It PMC_OP_CONFIGURE
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Configures the specified
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.Fa ctr
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prior to running.
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.Fa argp
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is a pointer to a
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.Em struct pmc_counter_cfg .
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.Bd -literal
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struct pmc_counter_cfg {
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pmc_evid_t event_id;
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pmc_ctr_t reset_value;
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uint32_t flags;
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};
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.Ed
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.Bl -tag -width width
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.It Dv event_id
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is the event ID to be counted.
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.It Dv reset_value
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is a value to which the counter should be reset on overflow (if supported
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by the implementation).
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This is most useful when profiling (see
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.Em PMC_OP_PROFSTART ,
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below).
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This value is defined to be the number of counter ticks before
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the next overflow.
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So, to get a profiling tick on every hundredth data cache miss, set the
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.Dv event_id
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to the proper value for
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.Dq dcache-miss
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and set
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.Dv reset_value
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to 100.
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.It Dv flags
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Currently unused.
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.El
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.It PMC_OP_PROFSTART
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Configures the specified
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.Fa ctr
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for use in profiling.
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.Fa argp
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is a pointer to a
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.Em struct pmc_counter_cfg
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as in
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.Em PMC_OP_CONFIGURE ,
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above.
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This request allocates a kernel counter, which will fail if any
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process is using the requested counter.
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Not all implementations or counters may support this option.
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.It PMC_OP_PROFSTOP
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Stops the specified
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.Fa ctr
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from being used for profiling.
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.Fa argp
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is ignored in this case and may be
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.Dv NULL .
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.El
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.Sh RETURN VALUES
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A return value of 0 indicates that the call succeeded.
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Otherwise, -1 is 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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.Sh ERRORS
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Among the possible error codes from
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.Fn pmc_control
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and
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.Fn pmc_get_info
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are
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.Bl -tag -width Er
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.It Bq Er EFAULT
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The address specified for the
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.Fa argp
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is invalid.
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.It Bq Er ENXIO
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Specified counter is not yet configured.
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.It Bq Er EINPROGRESS
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.Dv PMC_OP_START
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was passed for a counter that is already running.
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.It Bq Er EINVAL
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Specified counter was invalid.
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.It Bq Er EBUSY
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If the requested counter is already in use--either by the current process
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or by the kernel.
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.It Bq Er ENODEV
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If and only if the specified counter event is not valid for the specified
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counter when configuring a counter or starting profiling.
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.It Bq Er ENOMEM
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If the kernel is unable to allocate memory.
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.El
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.Sh SEE ALSO
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.Xr pmc 1 ,
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.Xr pmc 9
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.Sh HISTORY
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The
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.Fn pmc_control
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and
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.Fn pmc_get_info
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system calls appeared in
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.Nx 2.0 .
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