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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 (performance 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 num-
       ber 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 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
       performctl() 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 3.53 of the Linux man-pages project.  A description of the
       project,    and	  information	 about	  reporting    bugs,	can    be    found     at
       http://www.kernel.org/doc/man-pages/.

Linux					    2013-02-13				    PERFMONCTL(2)
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