2.6.(8.1) clock drift with apic enabled

[Quel Qun]

Hi,

Maybe a follow-up to http://groups.google.com/groups?q=time+drift
+group:fa.linux.kernel&hl=en&lr=&ie=UTF-8&group=fa.linux.kernel&selm=fa.kv2ep3o.6i053a%40ifi.uio.no&rnum=7

With 2.6 kernels (at least since 2.6.7), I observe a huge system time
drift (~12s/h) if I boot with apic enabled. If I boot with noapic
nolapic, the system time is stable. Of course, ntpd is stopped to get
the following results.

# cat /proc/cmdline
BOOT_IMAGE=linux-2681-2kk1 ro root=345 noapic nolapic nodevfs
pmdisk=/dev/hda6 splash=silent

# while (true) ; do ntpdate -q gateway ; sleep 300 ; done
Looking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset 0.000618, delay 0.02631
21 Aug 17:29:53 ntpdate[4636]: adjust time server 192.168.0.1 offset
0.000618 sec
Looking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset 0.000717, delay 0.02631
21 Aug 17:34:53 ntpdate[4645]: adjust time server 192.168.0.1 offset
0.000717 sec
Looking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset 0.000827, delay 0.02631
21 Aug 17:39:53 ntpdate[4654]: adjust time server 192.168.0.1 offset
0.000827 sec
Looking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset 0.000775, delay 0.02632
21 Aug 17:44:53 ntpdate[4663]: adjust time server 192.168.0.1 offset
0.000775 sec
Looking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset 0.000759, delay 0.02632
21 Aug 17:49:54 ntpdate[4672]: adjust time server 192.168.0.1 offset
0.000759 sec

# cat /proc/cmdline
BOOT_IMAGE=linux-2681-2kk1 ro root=345 nodevfs pmdisk=/dev/hda6
splash=silent

# while (true) ; do ntpdate -q gateway ; sleep 300 ; done
Looking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset -0.749909, delay 0.02631
21 Aug 17:59:27 ntpdate[4033]: step time server 192.168.0.1 offset
-0.749909 secLooking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset -1.865757, delay 0.02629
21 Aug 18:04:27 ntpdate[4044]: step time server 192.168.0.1 offset
-1.865757 secLooking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset -2.941571, delay 0.02631
21 Aug 18:09:27 ntpdate[4053]: step time server 192.168.0.1 offset
-2.941571 secLooking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset -4.057391, delay 0.02631
21 Aug 18:14:27 ntpdate[4062]: step time server 192.168.0.1 offset
-4.057391 secLooking for host gateway and service ntp
host found : gateway.home.net
server 192.168.0.1, stratum 2, offset -5.140378, delay 0.02631
21 Aug 18:19:27 ntpdate[4071]: step time server 192.168.0.1 offset
-5.140378 sec

At 12seconds/hour, the system is unusable. Hardware is an Asus A7N8X2 MB
with an Athlon XP 2100+

Please cc me directly if you need more info as I am not subscribed to
the list.

Thank you,
-- 
kk1

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