PERFALLOC(1)               General Commands Manual              PERFALLOC(1)

NAME         top

       perfalloc - notify pmdaperfevent(1) to disable hardware counter allo‐

SYNOPSIS         top

       $PCP_PMDAS_DIR/perfevent/perfalloc [-D] [-d] [-f lockfile] [-h] [-v]

DESCRIPTION         top

       perfalloc is a command that notifies the pmdaperfevent(1) to disable
       hardware counter event collection.  This allow unprivileged processes
       to use the hardware counters.

       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.

       Note that pmdaperfevent is affected by the value of the
       kernel.perf_event_paranoid setting, which can be adjusted by

       If a commandline is given, this is executed as a subprocess of the
       agent.  When the command dies, so does the agent.

       A brief description of the command line options follows:

       -D   run in the foreground (the default)

       -d   run in the background

       -f FILE
            use FILE as the lock file (default

       -h   display a help message and exit

       -v   output version number and exit

BUGS         top

       There may be a delay of up to 100 miliseconds between perfalloc
       requesting the hardware counter disabling and the perfevent pmda
       processing the request.

       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.

SEE ALSO         top

       pmdaperfevent(1), perfevent.conf(3) and sysctl(8).

COLOPHON         top

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Performance Co-Pilot                 PCP                        PERFALLOC(1)