[src/trunk]: src/sys/kern Adjust code that tries to prevent cc_microtime() fr...

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

details:   https://anonhg.NetBSD.org/src/rev/f5548995e159
branches:  trunk
changeset: 566730:f5548995e159
user:      nathanw <nathanw%NetBSD.org@localhost>
date:      Tue May 18 16:09:07 2004 +0000

description:
Adjust code that tries to prevent cc_microtime() from going backwards
so that it doesn't fire when called twice in the same microsecond,
which can lead to large error accumulation.

Appears to fix "repeated gettimeofday() goes backwards" on a fast
alpha and i386 box.

diffstat:

 sys/kern/kern_microtime.c |  6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diffs (27 lines):

diff -r e23ce6dd9d3c -r f5548995e159 sys/kern/kern_microtime.c
--- a/sys/kern/kern_microtime.c Tue May 18 16:08:33 2004 +0000
+++ b/sys/kern/kern_microtime.c Tue May 18 16:09:07 2004 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_microtime.c,v 1.4 2003/06/28 15:02:24 simonb Exp $        */
+/*     $NetBSD: kern_microtime.c,v 1.5 2004/05/18 16:09:07 nathanw Exp $       */
 
 /*-
  * Copyright (c) 2001 The NetBSD Foundation, Inc.
@@ -54,7 +54,7 @@
 
 #include <sys/cdefs.h>                 /* RCS ID & Copyright macro defns */
 
-__KERNEL_RCSID(0, "$NetBSD: kern_microtime.c,v 1.4 2003/06/28 15:02:24 simonb Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_microtime.c,v 1.5 2004/05/18 16:09:07 nathanw Exp $");
 
 #include "opt_multiprocessor.h"
 
@@ -137,7 +137,7 @@
                usec += 1000000;
                sec--;
        }
-       if (sec == 0) {
+       if (sec == 0 && usec > 0)  {
                t.tv_usec += usec + 1;
                if (t.tv_usec >= 1000000) {
                        t.tv_usec -= 1000000;