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   perfmonctl    ( 2 )

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Имя (Name)

perfmonctl - interface to IA-64 performance monitoring unit

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Синопсис (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.

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Описание (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.

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Возвращаемое значение (Return value)

perfmonctl() returns zero when the operation is successful.  On
       error, -1 is returned and errno is set to indicate the error.

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Версии (Versions)

perfmonctl() was added in Linux 2.4; it was removed in Linux
       5.10.

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Стандарты (Conforming to)

perfmonctl() is Linux-specific and is available only on the IA-64
       architecture.

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Примечание (Note)

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).

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Смотри также (See also)

gprof(1)

       The perfmon2 interface specification

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