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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  (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).