Date: Thu, 6 Jan 2011 13:00:24 GMT From: Anonymous <swell.k@gmail.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/78787: sysconf(_SC_CLK_TCK) may return incorrect value Message-ID: <201101061300.p06D0Ocn022680@freefall.freebsd.org>
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The following reply was made to PR kern/78787; it has been noted by GNATS.
From: Anonymous <swell.k@gmail.com>
To: Pete French <petefrench@ticketswitch.com>
Cc: bug-followup@FreeBSD.org
Subject: Re: kern/78787: sysconf(_SC_CLK_TCK) may return incorrect value
Date: Thu, 06 Jan 2011 15:52:08 +0300
The patch below borrows code from NetBSD and partially solves the issue.
It does not address all bde's concerns though
http://docs.freebsd.org/cgi/mid.cgi?20020701142849.U6692-100000
Also, on my amd64 box stathz != 128
kern.clockrate: { hz = 1000, tick = 1000, profhz = 8126, stathz = 127 }
--- a.diff begins here ---
Index: include/time.h
===================================================================
--- include/time.h (revision 216514)
+++ include/time.h (working copy)
@@ -50,8 +50,12 @@
* Frequency of the clock ticks reported by times(). Deprecated - use
* sysconf(_SC_CLK_TCK) instead. (Removed in 1003.1-2001.)
*/
-#define CLK_TCK 128
+#ifndef __lint
+__weak_reference(sysconf, __sysconf);
+long __sysconf(int);
#endif
+#define CLK_TCK (__sysconf(3))
+#endif
/* Frequency of the clock ticks reported by clock(). */
#define CLOCKS_PER_SEC 128
Index: lib/libc/gen/sysconf.c
===================================================================
--- lib/libc/gen/sysconf.c (revision 216473)
+++ lib/libc/gen/sysconf.c (working copy)
@@ -75,6 +75,8 @@ sysconf(name)
int mib[2], sverrno, value;
long lvalue, defaultresult;
const char *path;
+ struct clockinfo tmpclock;
+ static int clk_tck;
defaultresult = -1;
@@ -94,7 +96,21 @@ sysconf(name)
}
return ((long)rl.rlim_cur);
case _SC_CLK_TCK:
- return (CLK_TCK);
+ /*
+ * Has to be handled specially because it returns a
+ * struct clockinfo instead of an integer. Also, since
+ * this might be called often by some things that
+ * don't grok CLK_TCK can be a macro expanding to a
+ * function, cache the value.
+ */
+ if (clk_tck == 0) {
+ mib[0] = CTL_KERN;
+ mib[1] = KERN_CLOCKRATE;
+ len = sizeof(struct clockinfo);
+ clk_tck = sysctl(mib, 2, &tmpclock, &len, NULL, 0)
+ == -1 ? -1 : tmpclock.stathz;
+ }
+ return(clk_tck);
case _SC_NGROUPS_MAX:
mib[0] = CTL_KERN;
mib[1] = KERN_NGROUPS;
Index: usr.sbin/timed/timed/timed.c
===================================================================
--- usr.sbin/timed/timed/timed.c (revision 216514)
+++ usr.sbin/timed/timed/timed.c (working copy)
@@ -759,7 +759,8 @@
int force;
{
# define NG_DELAY (30*60*CLK_TCK) /* 30 minutes */
- static unsigned long last_update = -NG_DELAY;
+ static unsigned long last_update;
+ static int firsttime;
unsigned long new_update;
struct goodhost *ghp, **ghpp;
#ifdef HAVENIS
@@ -768,6 +769,10 @@
#endif /* HAVENIS */
struct tms tm;
+ if (firsttime == 0) {
+ last_update = -NG_DELAY;
+ firsttime++;
+ }
/* if no netgroup, then we are finished */
if (goodgroup == 0 || !Mflag)
--- a.diff ends here ---
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