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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 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
          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_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 4.09 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/.



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