kern/113670: wrong advertising of default value for HZ in sys/conf/NOTES

Ighighi ighighi at
Thu Jun 14 05:30:05 UTC 2007

>Number:         113670
>Category:       kern
>Synopsis:       wrong advertising of default value for HZ in sys/conf/NOTES
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jun 14 05:30:04 GMT 2007
>Originator:     Ighighi
>Release:        6.2-STABLE
FreeBSD orion 6.2-STABLE FreeBSD 6.2-STABLE #1: Tue Jun 12 20:39:04 VET 2007     root at orion:/usr/obj/usr/src/sys/CUSTOM  i386
The current src/sys/conf/NOTES (v1.1432) states that:



# The granularity of operation is controlled by the kernel option HZ whose
# default value (100) means a granularity of 10ms (1s/HZ).

options         HZ=100


I guess the real value is 10x that quantity for 4 of the "main" platforms,
as defined in src/sys/kern/subr_param.c


#ifndef HZ
#  if defined(__amd64__) || defined(__i386__) || defined(__ia64__) || defined(__sparc64__)
#    define     HZ 1000
#  else
#    define     HZ 100
#  endif


By looking at the CVS log available at:
it can be seen that it has been that way since 6.0-RELEASE, with a just a few
platforms being added earlier, and with no mention of it in their respective
GENERIC files, thus being the "real thing".

I just find it a bit misleading when compiling a new kernel and copy/pasting from NOTES. 



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