freebsd-skq/lib/libutil/kinfo_getvmmap.3

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.Dd May 10, 2020
.Dt KINFO_GETVMMAP 3
.Os
.Sh NAME
.Nm kinfo_getvmmap
.Nd function for getting per-process memory map information
.Sh LIBRARY
.Lb libutil
.Sh SYNOPSIS
.In sys/types.h
.In sys/user.h
.In libutil.h
.Ft struct kinfo_vmentry *
.Fn kinfo_getvmmap "pid_t pid" "int *cntp"
.Sh DESCRIPTION
This function is used for obtaining virtual memory mapping information
of a particular process.
.Pp
The
.Ar pid
field contains the process identifier.
This should be the a process that you have privilege to access.
The
.Ar cntp
field is allows the caller to know how many records are returned.
.Pp
This function is a wrapper around
.Xr sysctl 3
with the
.Dv KERN_PROC_VMMAP
mib.
While the kernel returns a packed structure, this function expands the
data into a fixed record format.
.Sh CAVEAT
.Fn kinfo_getvmmap
calls can cause significant CPU consumption because calculating the residency
counts requires iterating over all memory pages of the process.
Setting the sysctl variable
.Va kern.proc_vmmap_skip_resident_count
to 1 prevents this calculation.
.Sh RETURN VALUES
On success the
.Fn kinfo_getvmmap
function returns a pointer to an array of
.Vt struct kinfo_vmentry
structures as defined by
.In sys/user.h .
The array was obtained by an internal call to
.Xr malloc 3
and must be freed by the caller with a call to
.Xr free 3 .
On failure the
.Fn kinfo_getvmmap
function returns
.Dv NULL .
.Sh SEE ALSO
.Xr free 3 ,
.Xr kinfo_getfile 3 ,
.Xr malloc 3
.Sh HISTORY
The
.Fn kinfo_getvmmap
function first appeared in
.Fx 7.0 .