'\"macro stdmacro
.\"
.\" Copyright (c) 2014 Joseph White
.\"
.\" This program is free software; you can redistribute it and/or modify it
.\" under the terms of the GNU General Public License as published by the
.\" Free Software Foundation; either version 2 of the License, or (at your
.\" option) any later version.
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.\" WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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.\"
.TH PERFALLOC 1 "PCP" "Performance Co-Pilot"
.SH NAME
\f3perfalloc\f1 \- notify
.BR pmdaperfevent (1)
to disable hardware counter allocation.
.SH SYNOPSIS
\f3$PCP_PMDAS_DIR/perfevent/perfalloc\f1
[\f3\-D\f1]
[\f3\-d\f1]
[\f3\-f\f1 \f2lockfile\f1]
[\f3\-h\f1]
[\f3\-v\f1]
[\f3COMMAND\f1]
.SH DESCRIPTION
.B perfalloc
is a command that notifies the 
.BR pmdaperfevent (1)
to disable hardware counter event collection.
This allow unprivileged processes to use the hardware counters.
.PP
If the reservation request fails, then perfalloc exits immediately with
exit code EXIT_FAILURE.
If successful, the perfalloc will run until a kill signal is received.
The reservation request persists while perfalloc is running.
.PP
Note that
.B pmdaperfevent
is affected by the value of the
.I kernel.perf_event_paranoid
setting, which can be adjusted by
.BR sysctl (8).
.PP
If a commandline is given, this is executed as a subprocess of the agent.
When the command dies, so does the agent.
.PP
A brief description of the command line options follows:
.TP 5
.B \-D
run in the foreground (the default)
.TP
.B \-d
run in the background
.TP
.B \-f FILE
use FILE as the lock file (default $PCP_PMDAS_DIR/perfevent/perflock)
.TP
.B \-h
display a help message and exit
.TP
.B \-v
output version number and exit
.PD
.SH BUGS
There may be a delay of up to 100 miliseconds between perfalloc requesting the
hardware counter disabling and the perfevent pmda processing the request.
.PP
The perfalloc process does not check the status of the request and therefore is not able to
provide a positive confirmation that the request succeeded and the hardware counters are disabled.
.SH SEE ALSO
.BR pmdaperfevent (1),
.BR perfevent.conf (3)
and
.BR sysctl (8).