From a21cbcb876be978fa69925a758fcb12c4153e960 Mon Sep 17 00:00:00 2001
From: Andre Oppermann <andre@FreeBSD.org>
Date: Mon, 17 Oct 2005 15:37:22 +0000
Subject: [PATCH] Obtain true uptime through clock_gettime(CLOCK_MONOTONIC,
 struct *timespec) instead of subtracting 'bootime' from 'now'.

Sponsored by:	TCP/IP Optimization Fundraise 2005
---
 usr.bin/vmstat/vmstat.c | 20 ++++----------------
 usr.bin/w/w.c           | 12 +++---------
 2 files changed, 7 insertions(+), 25 deletions(-)

diff --git a/usr.bin/vmstat/vmstat.c b/usr.bin/vmstat/vmstat.c
index f52f7bfdf148..605319c68dcd 100644
--- a/usr.bin/vmstat/vmstat.c
+++ b/usr.bin/vmstat/vmstat.c
@@ -396,26 +396,14 @@ getdrivedata(char **argv)
 static long
 getuptime(void)
 {
-	static struct timeval boottime;
-	static time_t now;
+	struct timespec sp;
 	time_t uptime;
 
-	if (boottime.tv_sec == 0) {
-		if (kd != NULL) {
-			kread(X_BOOTTIME, &boottime, sizeof(boottime));
-		} else {
-			size_t size;
-
-			size = sizeof(boottime);
-			mysysctl("kern.boottime", &boottime, &size, NULL, 0);
-			if (size != sizeof(boottime))
-				errx(1, "kern.boottime size mismatch");
-		}
-	}
-	(void)time(&now);
-	uptime = now - boottime.tv_sec;
+	(void)clock_gettime(CLOCK_MONOTONIC, &sp);
+	uptime = sp.tv_sec;
 	if (uptime <= 0 || uptime > 60*60*24*365*10)
 		errx(1, "time makes no sense; namelist must be wrong");
+
 	return(uptime);
 }
 
diff --git a/usr.bin/w/w.c b/usr.bin/w/w.c
index 72559ba9b71f..8f69ab678563 100644
--- a/usr.bin/w/w.c
+++ b/usr.bin/w/w.c
@@ -424,9 +424,8 @@ pr_header(time_t *nowp, int nusers)
 {
 	double avenrun[3];
 	time_t uptime;
+	struct timespec tp;
 	int days, hrs, i, mins, secs;
-	int mib[2];
-	size_t size;
 	char buf[256];
 
 	/*
@@ -437,14 +436,9 @@ pr_header(time_t *nowp, int nusers)
 		(void)printf("%s ", buf);
 	/*
 	 * Print how long system has been up.
-	 * (Found by looking getting "boottime" from the kernel)
 	 */
-	mib[0] = CTL_KERN;
-	mib[1] = KERN_BOOTTIME;
-	size = sizeof(boottime);
-	if (sysctl(mib, 2, &boottime, &size, NULL, 0) != -1 &&
-	    boottime.tv_sec != 0) {
-		uptime = now - boottime.tv_sec;
+	if (clock_gettime(CLOCK_MONOTONIC, &tp) != -1) {
+		uptime = tp.tv_sec;
 		if (uptime > 60)
 			uptime += 30;
 		days = uptime / 86400;