Index: head/lib/libutil/kinfo_getvmmap.3
===================================================================
--- head/lib/libutil/kinfo_getvmmap.3	(revision 322664)
+++ head/lib/libutil/kinfo_getvmmap.3	(revision 322665)
@@ -1,79 +1,86 @@
 .\"
 .\" Copyright (c) 2008 Peter Wemm
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 .\"
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 .\" modification, are permitted provided that the following conditions
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 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 .\" $FreeBSD$
 .\"
-.Dd May 27, 2015
+.Dd August 18, 2017
 .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