Date: Mon, 18 Feb 2008 18:11:17 +0100 From: Martin Kammerhofer <dada@pluto.tugraz.at> To: dada@sbox.tugraz.at Subject: bin/120813: grdc(6) off by 500 ms (on average) Message-ID: <200802181711.m1IHBHI3021493@pluto.tugraz.at> Resent-Message-ID: <200802181800.m1II06LB084221@freefall.freebsd.org>
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>Number: 120813
>Category: bin
>Synopsis: grdc(6) off by 500 ms (on average)
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Mon Feb 18 18:00:06 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator: Martin Kammerhofer
>Release: FreeBSD 6.3-STABLE i386
>Organization:
TUG
>Environment:
System: FreeBSD Martin.liebt.Susi 6.3-STABLE FreeBSD 6.3-STABLE #1: Fri Feb 1 09:10:38 CET 2008 toor@Martin.liebt.Susi:/usr/obj/usr/src/sys/P2B-S i386
>Description:
The grdc(6) program (grand digital clock) draws (with curses) a
digital clock and refreshes the display once per second.
It uses sleep(1) in the main loop. Therefore the displayed clock
will be late by _off_, with 0 <= _off_ < 1 second.
On averagE it will be late half a second.
This is quite noticeable.
>How-To-Repeat:
Run /usr/games/grdc in an xterm window alongside a
xclock -update 1
and watch!
>Fix:
--- grdc.c.orig 2008-02-06 20:21:46.000000000 +0100
+++ grdc.c 2008-02-06 20:24:32.000000000 +0100
@@ -14,6 +14,7 @@
* $FreeBSD: src/games/grdc/grdc.c,v 1.12 2003/06/23 16:02:40 will Exp $
*/
+#include <sys/time.h>
#include <err.h>
#include <time.h>
#include <signal.h>
@@ -55,9 +56,7 @@
}
int
-main(argc, argv)
-int argc;
-char **argv;
+main (int argc, char **argv)
{
long t, a;
int i, j, s, k;
@@ -65,11 +64,16 @@
int ch;
int scrol;
int t12;
+int dflag = 0;
+struct timeval tv;
t12 = scrol = 0;
- while ((ch = getopt(argc, argv, "ts")) != -1)
+ while ((ch = getopt(argc, argv, "dts")) != -1)
switch (ch) {
+ case 'd':
+ dflag++;
+ break;
case 's':
scrol = 1;
break;
@@ -138,7 +142,12 @@
}
do {
mask = 0;
- time(&now);
+ if (gettimeofday(&tv, NULL))
+ err(2, "gettimeofday");
+ if (dflag)
+ warnx("woke up @ %ld.%06ld\n",
+ (long)tv.tv_sec, (long)tv.tv_usec);
+ now = tv.tv_sec;
tm = localtime(&now);
set(tm->tm_sec%10, 0);
set(tm->tm_sec/10, 4);
@@ -193,7 +202,10 @@
}
movto(6, 0);
refresh();
- sleep(1);
+ if (gettimeofday(&tv, NULL))
+ err(2, "gettimeofday");
+ if (tv.tv_sec == now)
+ usleep(1000000 - tv.tv_usec);
if (sigtermed) {
standend();
clear();
>Release-Note:
>Audit-Trail:
>Unformatted:
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