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Red Hat Bugzilla – Attachment 159325 Details for
Bug 248368
Enabling Hyperthreading on fc6 kernel 2.6.20-1.2952.fc6 or 2.6.20-1.2962.fc6 on IBM eseries x345 Xeon hardware makes kernel clock loose time like a bandit
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time drift measurements with ntpd off, varying HT enabled versus disabled.
kernel-time.txt (text/plain), 13.46 KB, created by
James Robinson
on 2007-07-16 14:34:49 UTC
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Description:
time drift measurements with ntpd off, varying HT enabled versus disabled.
Filename:
MIME Type:
Creator:
James Robinson
Created:
2007-07-16 14:34:49 UTC
Size:
13.46 KB
patch
obsolete
>Here's how fast it looses time -- about 1.5 seconds per each ~10 seconds. Start out with HT on, ntpd off, then >use ntpdate in debug mode to show time drift relative to our ntp master. Then, lower in the file, run same experiment >with HT disabled in the bios. Kernel accounts for time pretty much just fine -- or at least well within tolerance >for ntpd to keep it in sync. > >-------------------- > >HT ON > >[root@build-db02 ~]# uname -a >Linux build-db02.socialserve.com 2.6.20-1.2962.fc6 #1 SMP Tue Jun 19 18:24:12 EDT 2007 i686 i686 i386 GNU/Linux >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 10:02:20 ntpdate[2274]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02577, dispersion 0.00002 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f8ee.93365469 Mon, Jul 16 2007 10:02:22.575 >transmit timestamp: ca45f8ec.3968a505 Mon, Jul 16 2007 10:02:20.224 >filter delay: 0.02579 0.02579 0.02577 0.02579 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 2.350658 2.350649 2.350686 2.350683 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02577, dispersion 0.00002 >offset 2.350686 > >16 Jul 10:02:20 ntpdate[2274]: step time server 10.1.1.254 offset 2.350686 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 10:02:36 ntpdate[2278]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02577, dispersion 0.00002 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f900.b165d15c Mon, Jul 16 2007 10:02:40.692 >transmit timestamp: ca45f8fc.bfcd141a Mon, Jul 16 2007 10:02:36.749 >filter delay: 0.02580 0.02577 0.02579 0.02577 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 3.943578 3.943591 3.943602 3.943637 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02577, dispersion 0.00002 >offset 3.943591 > >16 Jul 10:02:36 ntpdate[2278]: step time server 10.1.1.254 offset 3.943591 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 10:02:47 ntpdate[2282]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02577, dispersion 0.00002 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f90c.e37e5862 Mon, Jul 16 2007 10:02:52.888 >transmit timestamp: ca45f907.df66a550 Mon, Jul 16 2007 10:02:47.872 >filter delay: 0.02583 0.02577 0.02579 0.02577 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 5.015806 5.015842 5.015851 5.015885 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02577, dispersion 0.00002 >offset 5.015842 > >16 Jul 10:02:47 ntpdate[2282]: step time server 10.1.1.254 offset 5.015842 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 10:02:58 ntpdate[2286]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02577, dispersion 0.00000 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f919.21ef4eee Mon, Jul 16 2007 10:03:05.132 >transmit timestamp: ca45f913.0a42aed1 Mon, Jul 16 2007 10:02:59.040 >filter delay: 0.02583 0.02579 0.02577 0.02577 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 6.092300 6.092321 6.092346 6.092375 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02577, dispersion 0.00000 >offset 6.092346 > >16 Jul 10:02:59 ntpdate[2286]: step time server 10.1.1.254 offset 6.092346 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 10:03:10 ntpdate[2290]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02577, dispersion 0.00000 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f925.65d0b428 Mon, Jul 16 2007 10:03:17.397 >transmit timestamp: ca45f91e.3a145953 Mon, Jul 16 2007 10:03:10.226 >filter delay: 0.02585 0.02577 0.02579 0.02599 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 7.170646 7.170690 7.170702 7.170620 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02577, dispersion 0.00000 >offset 7.170690 > >16 Jul 10:03:10 ntpdate[2290]: step time server 10.1.1.254 offset 7.170690 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 10:03:23 ntpdate[2294]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02576, dispersion 0.00003 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f933.aafd3173 Mon, Jul 16 2007 10:03:31.667 >transmit timestamp: ca45f92b.3e113404 Mon, Jul 16 2007 10:03:23.242 >filter delay: 0.02596 0.02576 0.02580 0.02576 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 8.425224 8.425339 8.425350 8.425384 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02576, dispersion 0.00003 >offset 8.425339 > >16 Jul 10:03:23 ntpdate[2294]: step time server 10.1.1.254 offset 8.425339 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 10:03:34 ntpdate[2298]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02577, dispersion 0.00002 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f93f.b6003310 Mon, Jul 16 2007 10:03:43.710 >transmit timestamp: ca45f936.3a04af92 Mon, Jul 16 2007 10:03:34.226 >filter delay: 0.02579 0.02577 0.02579 0.02577 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 9.484152 9.484158 9.484168 9.484199 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02577, dispersion 0.00002 >offset 9.484158 > >16 Jul 10:03:34 ntpdate[2298]: step time server 10.1.1.254 offset 9.484158 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 10:03:49 ntpdate[2303]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02577, dispersion 0.00002 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f950.3ab2eb48 Mon, Jul 16 2007 10:04:00.229 >transmit timestamp: ca45f945.4aecbfb1 Mon, Jul 16 2007 10:03:49.292 >filter delay: 0.02596 0.02577 0.02579 0.02577 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 10.93635 10.93646 10.93647 10.93651 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02577, dispersion 0.00002 >offset 10.936463 > >16 Jul 10:03:49 ntpdate[2303]: step time server 10.1.1.254 offset 10.936463 sec >[root@build-db02 ~]# > > >---------------- > >HT Off, ntpd off: > >[root@build-db02 ~]# uname -a >Linux build-db02.socialserve.com 2.6.20-1.2962.fc6 #1 SMP Tue Jun 19 18:24:12 EDT 2007 i686 i686 i386 GNU/Linux >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 09:51:52 ntpdate[2250]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02579, dispersion 0.00000 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f678.48018d20 Mon, Jul 16 2007 9:51:52.281 >transmit timestamp: ca45f678.41b06812 Mon, Jul 16 2007 9:51:52.256 >filter delay: 0.02591 0.02580 0.02579 0.02580 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 0.024508 0.024548 0.024555 0.024547 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02579, dispersion 0.00000 >offset 0.024555 > >16 Jul 09:51:52 ntpdate[2250]: adjust time server 10.1.1.254 offset 0.024555 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 09:52:40 ntpdate[2287]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02580, dispersion 0.00000 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f6a8.28a8cb41 Mon, Jul 16 2007 9:52:40.158 >transmit timestamp: ca45f6a8.27f67f4d Mon, Jul 16 2007 9:52:40.156 >filter delay: 0.02591 0.02582 0.02580 0.02582 > 0.00000 0.00000 0.00000 0.00000 >filter offset: 0.002560 0.002595 0.002600 0.002595 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02580, dispersion 0.00000 >offset 0.002600 > >16 Jul 09:52:40 ntpdate[2287]: adjust time server 10.1.1.254 offset 0.002600 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 09:52:57 ntpdate[2291]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02580, dispersion 0.00000 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f6b9.b94b1575 Mon, Jul 16 2007 9:52:57.723 >transmit timestamp: ca45f6b9.baa71583 Mon, Jul 16 2007 9:52:57.729 >filter delay: 0.02580 0.02582 0.02580 0.02582 > 0.00000 0.00000 0.00000 0.00000 >filter offset: -0.00540 -0.00543 -0.00543 -0.00543 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02580, dispersion 0.00000 >offset -0.005409 > >16 Jul 09:52:57 ntpdate[2291]: adjust time server 10.1.1.254 offset -0.005409 sec >[root@build-db02 ~]# sleep 10; ntpdate -d router >16 Jul 09:53:14 ntpdate[2295]: ntpdate 4.2.4p2@1.1495-o Thu Jun 21 12:57:42 UTC 2007 (1) >Looking for host router and service ntp >host found : router.socialserve.com >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >receive(10.1.1.254) >transmit(10.1.1.254) >server 10.1.1.254, port 123 >stratum 3, precision -20, leap 00, trust 000 >refid [10.1.1.254], delay 0.02576, dispersion 0.00002 >transmitted 4, in filter 4 >reference time: ca45f319.13d6bfea Mon, Jul 16 2007 9:37:29.077 >originate timestamp: ca45f6ca.f8c2f059 Mon, Jul 16 2007 9:53:14.971 >transmit timestamp: ca45f6ca.fc22ff08 Mon, Jul 16 2007 9:53:14.984 >filter delay: 0.02576 0.02582 0.02582 0.02582 > 0.00000 0.00000 0.00000 0.00000 >filter offset: -0.01326 -0.01331 -0.01331 -0.01330 > 0.000000 0.000000 0.000000 0.000000 >delay 0.02576, dispersion 0.00002 >offset -0.013264 > >16 Jul 09:53:14 ntpdate[2295]: adjust time server 10.1.1.254 offset -0.013264 sec >[root@build-db02 ~]# >
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bug 248368
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