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

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