perfmonctl(2)

1PERFMONCTL(2)              Linux Programmer's Manual             PERFMONCTL(2)
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NAME

6       perfmonctl - interface to IA-64 performance monitoring unit
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SYNOPSIS

9       #include <syscall.h>
10       #include <perfmon.h>
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12       long perfmonctl(int fd, int cmd, void *arg, int narg);
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14       Note: There is no glibc wrapper for this system call; see NOTES.
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DESCRIPTION

17       The  IA-64-specific  perfmonctl()  system call provides an interface to
18       the PMU (performance monitoring unit).  The PMU consists of  PMD  (per‐
19       formance  monitoring  data)  registers  and PMC (performance monitoring
20       control) registers, which gather hardware statistics.
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22       perfmonctl() applies the operation cmd to the input arguments specified
23       by  arg.   The number of arguments is defined by narg.  The fd argument
24       specifies the perfmon context to operate on.
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26       Supported values for cmd are:
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28       PFM_CREATE_CONTEXT
29              perfmonctl(int fd, PFM_CREATE_CONTEXT, pfarg_context_t *ctxt, 1);
30              Set up a context.
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32              The fd parameter is ignored.  A new perfmon context  is  created
33              as  specified  in  ctxt  and  its file descriptor is returned in
34              ctxt->ctx_fd.
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36              The file descriptor can be used in  subsequent  calls  to  perf‐
37              monctl()  and  can  be  used  to  read event notifications (type
38              pfm_msg_t) using read(2).  The file descriptor is pollable using
39              select(2), poll(2), and epoll(7).
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41              The context can be destroyed by calling close(2) on the file de‐
42              scriptor.
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44       PFM_WRITE_PMCS
45              perfmonctl(int fd, PFM_WRITE_PMCS, pfarg_reg_t *pmcs, n);
46              Set PMC registers.
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48       PFM_WRITE_PMDS
49              perfmonctl(int fd, PFM_WRITE_PMDS, pfarg_reg_t *pmds, n);
50              Set PMD registers.
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52       PFM_READ_PMDS
53              perfmonctl(int fd, PFM_READ_PMDS, pfarg_reg_t *pmds, n);
54              Read PMD registers.
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56       PFM_START
57              perfmonctl(int fd, PFM_START, NULL, 0);
58              Start monitoring.
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60       PFM_STOP
61              perfmonctl(int fd, PFM_STOP, NULL, 0);
62              Stop monitoring.
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64       PFM_LOAD_CONTEXT
65              perfmonctl(int fd, PFM_LOAD_CONTEXT, pfarg_load_t *largs, 1);
66              Attach the context to a thread.
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68       PFM_UNLOAD_CONTEXT
69              perfmonctl(int fd, PFM_UNLOAD_CONTEXT, NULL, 0);
70              Detach the context from a thread.
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72       PFM_RESTART
73              perfmonctl(int fd, PFM_RESTART, NULL, 0);
74              Restart monitoring after receiving an overflow notification.
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76       PFM_GET_FEATURES
77              perfmonctl(int fd, PFM_GET_FEATURES, pfarg_features_t *arg, 1);
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79       PFM_DEBUG
80              perfmonctl(int fd, PFM_DEBUG, val, 0);
81              If val is nonzero, enable debugging mode, otherwise disable.
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83       PFM_GET_PMC_RESET_VAL
84              perfmonctl(int fd, PFM_GET_PMC_RESET_VAL, pfarg_reg_t *req, n);
85              Reset PMC registers to default values.
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RETURN VALUE

88       perfmonctl() returns zero when the operation is successful.  On  error,
89       -1 is returned and errno is set to indicate the error.
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VERSIONS

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

95       perfmonctl()  is  Linux-specific and is available only on the IA-64 ar‐
96       chitecture.
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NOTES

99       This system call was broken for many years, and ultimately  removed  in
100       Linux 5.10.
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102       Glibc does not provide a wrapper for this system call; on kernels where
103       it exists, call it using syscall(2).
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COLOPHON

111       This page is part of release 5.12 of the Linux  man-pages  project.   A
112       description  of  the project, information about reporting bugs, and the
113       latest    version    of    this    page,    can     be     found     at
114       https://www.kernel.org/doc/man-pages/.
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118Linux                             2021-03-22                     PERFMONCTL(2)