From fb4754735a456928de94c30ae8f10b15b654564a Mon Sep 17 00:00:00 2001
From: sevan <sevan@ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f>
Date: Sun, 25 Mar 2018 01:33:51 +0000
Subject: [PATCH] MFC r322665

Add caveat to kinfo_getvmmap(3) explaining high CPU utilisation.
Based on kib's reply on https://lists.freebsd.org/pipermail/freebsd-hackers/2016-July/049710.html


git-svn-id: svn://svn.freebsd.org/base/stable/10@331517 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
---
 lib/libutil/kinfo_getvmmap.3 | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/libutil/kinfo_getvmmap.3 b/lib/libutil/kinfo_getvmmap.3
index c6a13700a..134b20a56 100644
--- a/lib/libutil/kinfo_getvmmap.3
+++ b/lib/libutil/kinfo_getvmmap.3
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd May 27, 2015
+.Dd August 18, 2017
 .Dt KINFO_GETVMMAP 3
 .Os
 .Sh NAME
@@ -58,6 +58,13 @@ with the
 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
-- 
2.42.0