[src/trunk]: src/lib/libc/sys mention how HZ affects us

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

details:   https://anonhg.NetBSD.org/src/rev/d382cbb855d3
branches:  trunk
changeset: 326540:d382cbb855d3
user:      christos <christos%NetBSD.org@localhost>
date:      Sat Feb 01 22:42:45 2014 +0000

description:
mention how HZ affects us

diffstat:

 lib/libc/sys/nanosleep.2 |  16 ++++++++++++++--
 1 files changed, 14 insertions(+), 2 deletions(-)

diffs (34 lines):

diff -r 901ee25c95b2 -r d382cbb855d3 lib/libc/sys/nanosleep.2
--- a/lib/libc/sys/nanosleep.2  Sat Feb 01 21:05:54 2014 +0000
+++ b/lib/libc/sys/nanosleep.2  Sat Feb 01 22:42:45 2014 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: nanosleep.2,v 1.14 2013/12/25 00:58:50 dholland Exp $
+.\"    $NetBSD: nanosleep.2,v 1.15 2014/02/01 22:42:45 christos Exp $
 .\"
 .\" Copyright (c) 1986, 1991, 1993
 .\"    The Regents of the University of California.  All rights reserved.
@@ -29,7 +29,7 @@
 .\"
 .\"     @(#)sleep.3    8.1 (Berkeley) 6/4/93
 .\"
-.Dd October 1, 2012
+.Dd February 1, 2014
 .Dt NANOSLEEP 2
 .Os
 .Sh NAME
@@ -163,3 +163,15 @@
 .Fn clock_nanosleep
 function conforms to
 .St -p1003.1j-2000 .
+.Sh BUGS
+The
+.Nx
+kernel is not tickless, so the maximum sleep resolution is determined
+by the value of
+.Dv HZ
+which is by default
+.Dv 100
+in most architectures.
+This means that a request to sleep for less than
+.Dv 10ms
+(1 / HZ seconds), is rounded up to that.