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 argument
       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	 perf-
	      monctl()	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_FEATURES, 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

COLOPHON
       This  page  is  part of release 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest	  version     of     this    page,    can    be	   found    at
       https://www.kernel.org/doc/man-pages/.



Linux				  2013-02-13			 PERFMONCTL(2)