[src/trunk]: src/share/man/man4 Update the description of the NMBCLUSTERS. Ad...

[msaitoh <msaitoh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/6e5cfd07480c
branches:  trunk
changeset: 1023983:6e5cfd07480c
user:      msaitoh <msaitoh%NetBSD.org@localhost>
date:      Wed Oct 06 05:25:53 2021 +0000

description:
Update the description of the NMBCLUSTERS. Add NMBCLUSTERS_MAX.

diffstat:

 share/man/man4/options.4 |  15 ++++++++++-----
 1 files changed, 10 insertions(+), 5 deletions(-)

diffs (34 lines):

diff -r e144d8432454 -r 6e5cfd07480c share/man/man4/options.4
--- a/share/man/man4/options.4  Wed Oct 06 05:24:54 2021 +0000
+++ b/share/man/man4/options.4  Wed Oct 06 05:25:53 2021 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: options.4,v 1.519 2021/06/03 20:18:06 riastradh Exp $
+.\"    $NetBSD: options.4,v 1.520 2021/10/06 05:25:53 msaitoh Exp $
 .\"
 .\" Copyright (c) 1996
 .\"    Perry E. Metzger.  All rights reserved.
@@ -2076,15 +2076,20 @@
 This is used to compute the size of the kernel VM map
 .Em mb_map ,
 which maps mbuf clusters.
-Default on most ports is 1024 (2048 with
-.Dq options GATEWAY
-).
+The default value is calculated from the amount of physical memory.
+Architectures without direct mapping also limit it based on the kmem_map size,
+which is used as backing store.
+Some archs limit the value with
+.Sq NMBCLUSTERS_MAX .
 See
 .Pa /usr/include/machine/param.h
-for exact default information.
+for those archs.
+This value can be accessed via the kern.mbuf.nmbclusters sysctl variable.
 Increase this value if you get
 .Dq mclpool limit reached
 messages.
+.It Cd options NMBCLUSTERS_MAX=value
+The upper limit of NMBCLUSTERS.
 .It Cd options NKMEMPAGES=value
 .It Cd options NKMEMPAGES_MIN=value
 .It Cd options NKMEMPAGES_MAX=value