PERFMONCTL(2)						     Linux Programmer's Manual						     PERFMONCTL(2)

NAME

       perfmonctl - interface to IA-64 performance monitoring unit

SYNOPSIS

       #include <syscall.h>
       #include <perfmon.h>

       long perfmonctl(int fd, int cmd, void *arg, int narg);
       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION

       The  IA-64-specific perfmonctl() system call provides an interface to the PMU (performance monitoring unit).  The PMU consists of PMD (per-
       formance monitoring data) registers and PMC (performance monitoring control) registers, which gather hardware statistics.

       perfmonctl() applies the operation cmd to the input arguments specified by arg.	The number of arguments is defined by narg.  The fd  argu-
       ment specifies the perfmon context to operate on.

       Supported values for cmd are:

       PFM_CREATE_CONTEXT
	      perfmonctl(int fd, PFM_CREATE_CONTEXT, pfarg_context_t *ctxt, 1);
	      Set up a context.

	      The  fd  parameter  is  ignored.	 A  new  perfmon  context  is  created as specified in ctxt and its file descriptor is returned in
	      ctxt->ctx_fd.

	      The file descriptor can be used in subsequent calls to perfmonctl() and can be used to read  event  notifications  (type	pfm_msg_t)
	      using read(2).  The file descriptor is pollable using select(2), poll(2), and epoll(7).

	      The context can be destroyed by calling close(2) on the file descriptor.

       PFM_WRITE_PMCS
	      perfmonctl(int fd, PFM_WRITE_PMCS, pfarg_reg_t *pmcs, n);
	      Set PMC registers.

       PFM_WRITE_PMDS
	      perfmonctl(int fd, PFM_WRITE_PMDS, pfarg_reg_t *pmds, n);
	      Set PMD registers.

       PFM_READ_PMDS
	      perfmonctl(int fd, PFM_READ_PMDS, pfarg_reg_t *pmds, n);
	      Read PMD registers.

       PFM_START
	      perfmonctl(int fd, PFM_START, NULL, 0);
	      Start monitoring.

       PFM_STOP
	      perfmonctl(int fd, PFM_STOP, NULL, 0);
	      Stop monitoring.

       PFM_LOAD_CONTEXT
	      perfmonctl(int fd, PFM_LOAD_CONTEXT, pfarg_load_t *largs, 1);
	      Attach the context to a thread.

       PFM_UNLOAD_CONTEXT
	      perfmonctl(int fd, PFM_UNLOAD_CONTEXT, NULL, 0);
	      Detach the context from a thread.

       PFM_RESTART
	      perfmonctl(int fd, PFM_RESTART, NULL, 0);
	      Restart monitoring after receiving an overflow notification.

       PFM_GET_FEATURES
	      perfmonctl(int fd, PFM_GET_FEARURES, pfarg_features_t *arg, 1);

       PFM_DEBUG
	      perfmonctl(int fd, PFM_DEBUG, val, 0);
	      If val is nonzero, enable debugging mode, otherwise disable.

       PFM_GET_PMC_RESET_VAL
	      perfmonctl(int fd, PFM_GET_PMC_RESET_VAL, pfarg_reg_t * req, n);
	      Reset PMC registers to default values.

RETURN VALUE

       perfmonctl() returns zero when the operation is successful.  On error, -1 is returned and errno is set to indicate the cause of the error.

VERSIONS

       perfmonctl() is available since Linux 2.4.

CONFORMING TO

       perfmonctl() is Linux-specific and is available only on the IA-64 architecture.

NOTES

       Glibc does not provide a wrapper for this system call; call it using syscall(2).

SEE ALSO

       gprof(1)

       The perfmon2 interface specification

Linux								    2013-02-13							     PERFMONCTL(2)