[src/trunk]: src/share/man/man4 actually MBUFTRACE does splvm(), kpreempt_dis...

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

details:   https://anonhg.NetBSD.org/src/rev/183a6edacf32
branches:  trunk
changeset: 1009488:183a6edacf32
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Fri Apr 24 13:47:50 2020 +0000

description:
actually MBUFTRACE does splvm(), kpreempt_disable()/enable() and percpu,
this has non-slight overhead - amend documentation to stop claiming
the overhead is slight

adresses PR port-xen/50290

diffstat:

 share/man/man4/options.4 |  7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diffs (21 lines):

diff -r 85c97a91b342 -r 183a6edacf32 share/man/man4/options.4
--- a/share/man/man4/options.4  Fri Apr 24 13:34:47 2020 +0000
+++ b/share/man/man4/options.4  Fri Apr 24 13:47:50 2020 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: options.4,v 1.510 2020/04/04 15:32:42 jdolecek Exp $
+.\"    $NetBSD: options.4,v 1.511 2020/04/24 13:47:50 jdolecek Exp $
 .\"
 .\" Copyright (c) 1996
 .\"    Perry E. Metzger.  All rights reserved.
@@ -1965,8 +1965,9 @@
 .Em pseudo-device ipfilter .
 .It Cd options MBUFTRACE
 This option can help track down mbuf leaks.
-When enabled, mbufs are tagged with the devices and protocols using them,
-which slightly decreases network performance.
+When enabled, mbufs are tagged with the devices and protocols using them.
+This can significantly decrease network performance, particularly
+on MP systems.
 This additional information can be viewed with
 .Xr netstat 1 :
 .Dl Ic netstat Fl mssv