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PMC_ALLOCATE(3)		 BSD Library Functions Manual	       PMC_ALLOCATE(3)

     pmc_allocate, pmc_release -- allocate and free performance	monitoring

     Performance Counters Library (libpmc, -lpmc)

     #include <pmc.h>

     pmc_allocate(const	char *eventspecifier, enum pmc_mode mode,
	 uint32_t flags, int cpu, pmc_id_t *pmcid);

     pmc_release(pmc_id_t pmc);

     Function pmc_allocate() allocates a performance monitoring	counter	that
     measures the events named by argument eventspecifier, and writes the al-
     located handle to the location pointed to by argument pmcid.

     Argument eventspecifier comprises an PMC event name followed by an	op-
     tional comma separated list of keywords and qualifiers.  The allowed syn-
     tax for argument eventspecifier is	processor specific and is listed in
     section EVENT SPECIFIERS in the pmc(3) manual page.

     The desired PMC mode is specified by argument mode.  Legal	values for the
     mode argument are:
     PMC_MODE_SC  Allocate a system-scope counting PMC.
     PMC_MODE_SS  Allocate a system-scope sampling PMC.
     PMC_MODE_TC  Allocate a process-scope counting PMC.
     PMC_MODE_TS  Allocate a process-scope sampling PMC.

     Mode specific modifiers may be specified using argument flags.  The flags
     supported at PMC allocation time are:
     PMC_F_DESCENDANTS	 For process-scope PMCs, automatically track descen-
			 dants of attached processes.
     PMC_F_LOG_PROCCSW	 For process-scope counting PMCs, generate a log event
			 at every context switch containing the	incremental
			 number	of hardware events seen	by the process during
			 the time it was executing on the CPU.
     PMC_F_LOG_PROCEXIT	 For process-scope counting PMCs, accumulate hardware
			 events	seen when the process was executing on a CPU
			 and generate a	log event when an attached process ex-
     PMCs allocated with flags PMC_F_LOG_PROCCSW and PMC_F_LOG_PROCEXIT	need a
     log file to be configured before they are started.

     For system	scope PMCs, the	argument cpu is	a non-negative value that
     specifies the CPU number that the PMC is to be allocated on.  Process
     scope PMC allocations should specify the constant PMC_CPU_ANY for this

     Function pmc_release() releases the PMC denoted by	argument pmcid.

     If	successful, function pmc_allocate() sets the location specified	by ar-
     gument pmcid to the handle	of the allocated PMC and returns 0.  In	case
     of	an error, the function returns -1 and sets the global variable errno
     to	indicate the error.

     The pmc_release() function	returns	the value 0 if successful; otherwise
     the value -1 is returned and the global variable errno is set to indicate
     the error.

     [EINVAL]		The argument mode to function pmc_allocate() had an
			invalid	value.

     [EINVAL]		Argument cpu to	function pmc_allocate()	had an invalid
			CPU number.

     [EINVAL]		Argument flags contained flags that were unsupported
			or otherwise incompatible with the requested PMC mode.

     [EINVAL]		Argument eventspecifier	to function pmc_allocate()
			specified an event not supported by hardware or	con-
			tained a syntax	error.

     [ENXIO]		Function pmc_allocate()	requested the use of a hard-
			ware resource that was absent or administratively dis-

     [EOPNOTSUPP]	The underlying hardware	does not support the capabili-
			ties needed for	a PMC being allocated by a call	to

     [EPERM]		A system scope PMC allocation was attempted without
			adequate process privilege.

     [ESRCH]		Function pmc_release() was called without first	having
			allocated a PMC.

     [EINVAL]		Argument pmcid to function pmc_release() did not spec-
			ify a PMC previously allocated by this process.

     pmc(3), pmc_attach(3), pmc_configure_logfile(3), pmc_start(3), hwpmc(4)

BSD			      September	22, 2008			   BSD


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