xref: /freebsd/lib/libutil/kinfo_getvmmap.3 (revision d37eb51047221dc3322b34db1038ff3aa533883f)
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26.Dd May 10, 2020
27.Dt KINFO_GETVMMAP 3
28.Os
29.Sh NAME
30.Nm kinfo_getvmmap
31.Nd function for getting per-process memory map information
32.Sh LIBRARY
33.Lb libutil
34.Sh SYNOPSIS
35.In sys/types.h
36.In sys/user.h
37.In libutil.h
38.Ft struct kinfo_vmentry *
39.Fn kinfo_getvmmap "pid_t pid" "int *cntp"
40.Sh DESCRIPTION
41This function is used for obtaining virtual memory mapping information
42of a particular process.
43.Pp
44The
45.Ar pid
46field contains the process identifier.
47This should be the a process that you have privilege to access.
48The
49.Ar cntp
50field is allows the caller to know how many records are returned.
51.Pp
52This function is a wrapper around
53.Xr sysctl 3
54with the
55.Dv KERN_PROC_VMMAP
56mib.
57While the kernel returns a packed structure, this function expands the
58data into a fixed record format.
59.Sh RETURN VALUES
60On success the
61.Fn kinfo_getvmmap
62function returns a pointer to an array of
63.Vt struct kinfo_vmentry
64structures as defined by
65.In sys/user.h .
66The array was obtained by an internal call to
67.Xr malloc 3
68and must be freed by the caller with a call to
69.Xr free 3 .
70On failure the
71.Fn kinfo_getvmmap
72function returns
73.Dv NULL .
74.Sh SEE ALSO
75.Xr free 3 ,
76.Xr kinfo_getfile 3 ,
77.Xr malloc 3
78.Sh HISTORY
79The
80.Fn kinfo_getvmmap
81function first appeared in
82.Fx 7.0 .
83.Sh CAVEATS
84.Fn kinfo_getvmmap
85calls can cause significant CPU consumption because calculating the residency
86counts requires iterating over all memory pages of the process.
87Setting the sysctl variable
88.Va kern.proc_vmmap_skip_resident_count
89to 1 prevents this calculation.
90