perfmonctl(2) - Linux manual page (original) (raw)

perfmonctl(2) System Calls Manual perfmonctl(2)

NAME top

   perfmonctl - interface to IA-64 performance monitoring unit

SYNOPSIS top

   **#include <syscall.h>**
   **#include <perfmon.h>**

   **long perfmonctl(int** _fd_**, int** _cmd_**, void** _arg_**[.**_narg_**], int** _narg_**);**

   _Note_: There is no glibc wrapper for this system call; see HISTORY.

DESCRIPTION top

   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->ctxfd_.

          The file descriptor can be used in subsequent calls to
          **perfmonctl**() and can be used to read event notifications
          (type _pfmmsgt_) using [read(2)](../man2/read.2.html).  The file descriptor is
          pollable using [select(2)](../man2/select.2.html), [poll(2)](../man2/poll.2.html), and [epoll(7)](../man7/epoll.7.html).

          The context can be destroyed by calling [close(2)](../man2/close.2.html) 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 top

   **perfmonctl**() returns zero when the operation is successful.  On
   error, -1 is returned and _[errno](../man3/errno.3.html)_ is set to indicate the error.

STANDARDS top

   Linux on IA-64.

HISTORY top

   Added in Linux 2.4; removed in Linux 5.10.

   This system call was broken for many years, and ultimately removed
   in Linux 5.10.

   glibc does not provide a wrapper for this system call; on kernels
   where it exists, call it using [syscall(2)](../man2/syscall.2.html).

SEE ALSO top

   [gprof(1)](../man1/gprof.1.html)

   The perfmon2 interface specification

COLOPHON top

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Linux man-pages 6.10 2024-05-02 perfmonctl(2)

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