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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-users] ntpd under Xen Dom0 exhibits extremely high jitter/noise? runs stable/quiet under non-xen kernel.
What platform timer does Xen say is initialised during boot? Possibly Xen's 'clocksource=' boot option could be used to select a different platform timer exhibiting less jitter. Tbh I don't think we've ever done a detailed analysis of ntp performance on Xen before -- this is something we might be able to improve. -- Keir On 17/01/2010 20:22, "Pasi Kärkkäinen" <pasik@xxxxxx> wrote: > > Keir and others, > > Please check the table in the end of the mail below.. is there > hypervisor (boot time) option to make it behave better for ntpd? > > -- Pasi > > On Sat, Jan 16, 2010 at 11:17:36AM -0800, mail ignored wrote: >> On Thu, Jan 14, 2010 at 8:20 PM, Fajar A. Nugraha <fajar@xxxxxxxxx> wrote: >>>> @ novell say it's xen & ntp >>>> @ ntp say it's novell & xen >>>> @ xen say it's novell & ntp >>>> >> >>> That's why I suggested you use a workaround: use 2.6.18 kernel, either >>> from RHEL or from xen.org :D >>> If this works -> novell problem >>> If this doesn't work -> xen problem >> >> On Sat, Jan 16, 2010 at 5:05 AM, Fajar A. Nugraha <fajar@xxxxxxxxx> wrote: >>> You might want to try latest pv_ops as well >>> (http://wiki.xensource.com/xenwiki/XenParavirtOps), which should be >>> easier to work with Opensuse since the version number is close. >> >> it seems it's _not_ the kernel -- unless there's a coincident kernel >> problem across source/vendor ... >> >> per >> http://lists.xensource.com/archives/html/xen-devel/2009-12/msg01127.html >> http://wiki.xensource.com/xenwiki/XenParavirtOps >> http://wiki.xensource.com/xenwiki/Kernel.org_Linux_on_Xen >> >> cd /home/workspace && rm -rf linux-2.6-xen >> git clone git://git.kernel.org/pub/scm/linux/kernel/git/jeremy/xen.git >> linux-2.6-xen >> cd linux-2.6-xen >> make clean >> cp -a .config .config-old >> wget -O .config >> http://pasik.reaktio.net/xen/pv_ops-dom0-debug/config-2.6.31.4-pvops_dom0-x86 >> _64 >> make oldconfig >> ... >> Xen PCI Frontend (XEN_PCIDEV_FRONTEND) [N/m/y/?] (NEW) <-- m >> ... >> "IMQ" target support (NETFILTER_XT_TARGET_IMQ) [N/m/?] (NEW) <-- m >> ... >> IMQ (intermediate queueing device) support (IMQ) [M/y/?] (NEW) <-- >> [enter] >> ... >> Block-device tap backend driver (XEN_BLKDEV_TAP) [N/m/y/?] (NEW) <-- m >> ... >> >> make bzImage >> make modules >> make modules_install >> strip vmlinux -o vmlinux-stripped >> gzip vmlinux-stripped -c > vmlinuz-gzipped >> >> ls -al .config \ >> System.map \ >> arch/x86/boot/bzImage \ >> vmlinux \ >> vmlinux-stripped \ >> vmlinuz-gzipped >> >> cp -a .config /boot/config-2.6.31.6 >> cp -a System.map /boot/System.map-2.6.31.6 >> cp -a arch/x86/boot/bzImage /boot/vmlinuz-2.6.31.6 >> mkinitrd >> ls -al /boot/*2.6.31.6* >> -rw-r--r-- 1 root root 98510 2010-01-16 03:02 /boot/config-2.6.31.6 >> -rw-r--r-- 1 root root 21304611 2010-01-16 04:14 /boot/initrd-2.6.31.6 >> -rw-r--r-- 1 root root 1940879 2010-01-16 03:14 /boot/System.map-2.6.31.6 >> -rw-r--r-- 1 root root 3751936 2010-01-16 03:14 /boot/vmlinuz-2.6.31.6 >> >> >> vi /boot/grub/menu.lst >> ... >> title xen.git >> root (hd0,0) >> kernel /xen.gz loglvl=all loglvl_guest=all dom0_mem=1024M >> vga=gfx-1280x1024x32 console=vga,com1 com1=57600,8n1 >> module /vmlinuz-2.6.31.6 root=/dev/VG0/ROOT rootfstype=ext4 >> rootflags=journal_checksum resume=/dev/VG0/SWAP nomodeset selinux=0 >> SELINUX_INIT=NO vga=0x31a console=tty0 console=xvc0,57600 >> module /initrd-2.6.31.6 >> >> title xen.git DISABLED >> root (hd0,0) >> kernel /vmlinuz-2.6.31.6 root=/dev/VG_SVR/LV_SVR_DOM0_ROOT >> rootfstype=ext4 rootflags=journal_checksum >> resume=/dev/VG_SVR/LV_SVR_DOM0_SWAP nomodeset showopts splash=silent >> selinux=0 SELINUX_INIT=NO elevator=cfq vga=0x31a console=tty0 >> console=ttyS0,57600n8 >> module /initrd-2.6.31.6 >> ... >> >> >> boot to "xen.git" >> >> uname -a >> Linux test 2.6.31.6 #1 SMP Sat Jan 16 03:14:19 PST 2010 x86_64 >> x86_64 x86_64 GNU/Linux >> lsb_release -a >> LSB Version: >> core-2.0-noarch:core-3.2-noarch:core-4.0-noarch:core-2.0-x86_64:core-3.2-x86_ >> 64:core-4.0-x86_64:desktop-4.0-amd64:desktop-4.0-noarch:graphics-2.0-amd64:gr >> aphics-2.0-noarch:graphics-3.2-amd64:graphics-3.2-noarch:graphics-4.0-amd64:g >> raphics-4.0-noarch >> Distributor ID: SUSE LINUX >> Description: openSUSE 11.2 (x86_64) >> Release: 11.2 >> Codename: n/a >> >> service ntp stop >> rm /etc/adjtime /var/ >> rm /var/lib/ntp/drift/ntp.drift >> >> cat << EOF > /etc/sysconfig/clock >> HWCLOCK="--utc" >> SYSTOHC="yes" >> TIMEZONE="America/Los_Angeles" >> DEFAULT_TIMEZONE="US/Pacific" >> EOF >> hwclock --systohc --utc >> service ntp start >> >> sntp clock.isc.org && date && hwclock --utc --show >> 2010 Jan 16 04:37:09.000729 + 1.435060 +/- 0.028944 secs >> Sat Jan 16 04:37:11 PST 2010 >> Sat 16 Jan 2010 04:37:11 AM PST -0.345191 seconds >> >> ... (wait ~ 6 hours) ... >> >> date >> Sat Jan 16 11:01:42 PST 2010 >> ntpq -p -c rv >> assID=0 status=06c4 leap_none, sync_ntp, 12 events, event_peer/strat_chg, >> version="ntpd 4.2.4p8@xxxxxx Mon Dec 28 17:26:30 UTC 2009 (1)", >> processor="x86_64", system="Linux/2.6.31.6", leap=00, stratum=2, >> precision=-20, rootdelay=14.718, rootdispersion=135.995, peer=11390, >> refid=66.220.9.122, >> reftime=cefc89b2.a36f1342 Sat, Jan 16 2010 10:53:38.638, poll=6, >> clock=cefc8b82.7e523feb Sat, Jan 16 2010 11:01:22.493, state=2, >> offset=-115.130, frequency=-500.000, jitter=464.242, noise=29.343, >> stability=154.680 >> remote refid st t when poll reach delay offset jitter >> =============================================================================>> = >> *clock.fmt.he.ne .PPS. 1 u 29 64 377 21.438 -811.68 >> 462.837 >> +otc2.psu.edu 129.6.15.29 2 u 7 64 377 109.399 -850.99 >> 470.522 >> +clock.isc.org .GPS. 1 u 7 64 377 21.440 -854.82 >> 468.274 >> +clock.sjc.he.ne .CDMA. 1 u 49 64 377 16.889 -780.55 >> 469.481 >> +zorro.sf-bay.or 216.218.254.202 2 u 59 64 377 20.366 -762.14 >> 458.947 >> +nist1.aol-ca.tr .ACTS. 1 u 38 64 377 16.260 -795.87 >> 463.170 >> >> boot to "xen.git DISABLED" >> >> uname -a >> Linux test 2.6.31.6 #1 SMP Sat Jan 16 09:14:19 PST 2010 x86_64 x86_64 >> x86_64 GNU/Linux >> >> service ntp stop >> rm /etc/adjtime /var/ >> rm /var/lib/ntp/drift/ntp.drift >> service ntp start >> >> ... (wait ~ 10 minutes) ... >> date >> Sat Jan 16 11:15:05 PST 2010 >> ntpq -p -c rv >> assID=0 status=0664 leap_none, sync_ntp, 6 events, event_peer/strat_chg, >> version="ntpd 4.2.4p8@xxxxxx Mon Dec 28 17:26:30 UTC 2009 (1)", >> processor="x86_64", system="Linux/2.6.31.6", leap=00, stratum=2, >> precision=-20, rootdelay=22.750, rootdispersion=975.184, peer=43091, >> refid=66.220.9.122, >> reftime=cefc8c7c.35ca466a Sat, Jan 16 2010 11:05:32.210, poll=6, >> clock=cefc8eb9.25103a1f Sat, Jan 16 2010 11:15:05.144, state=3, >> offset=27.534, frequency=0.000, jitter=6.740, noise=16.331, >> stability=0.000 >> remote refid st t when poll reach delay offset jitter >> =============================================================================>> = >> *clock.fmt.he.ne .PPS. 1 u 4 64 377 18.112 10.541 >> 5.892 >> +otc2.psu.edu 147.84.59.145 2 u 64 64 377 101.103 12.106 >> 8.621 >> +clock.isc.org .GPS. 1 u 57 64 377 14.990 4.830 >> 9.622 >> +clock.sjc.he.ne .CDMA. 1 u 59 64 377 16.503 9.299 >> 9.440 >> +zorro.sf-bay.or 216.218.254.202 2 u 56 64 377 22.212 6.323 >> 11.031 >> +nist1.aol-ca.tr .ACTS. 1 u 60 64 377 17.076 14.316 >> 9.260 >> >> in summary, >> >> kernel OS/distro xen timekeeping >> ------------------------------------- --------------- ------- ------------ >> opensuse kernel-default-2.6.31.8-0.1 opensuse 11.2 (n/a) OK >> opensuse kernel-default-2.6.32-41 opensuse 11.2 (n/a) OK >> opensuse kernel-xen-2.6.31.8-0.1 opensuse 11.2 3.4.x NOISY/FAIL >> opensuse kernel-xen-2.6.32-41 opensuse 11.2 3.4.x NOISY/FAIL >> opensuse kernel-xen-2.6.31.8-0.1 opensuse 11.2 4.0.x NOISY/FAIL >> opensuse kernel-xen-2.6.32-41 opensuse 11.2 4.0.x NOISY/FAIL >> xen.git kernel-2.6.31.6 (pvops Dom0) opensuse 11.2 4.0.x NOISY/FAIL >> xen.git kernel-2.6.31.6 opensuse 11.2 (n/a) OK >> >> i.e., >> >> 3 different kernel versions, from two different vendors, have >> low-noise/accurate timekeeping in NON-xen configs. >> >> boot any of those kernels with either v34x or v40x hypervisor in >> place, and timekeeping suffers from unusably excessive jitter & >> offset. >> >> _______________________________________________ >> Xen-users mailing list >> Xen-users@xxxxxxxxxxxxxxxxxxx >> http://lists.xensource.com/xen-users _______________________________________________ Xen-users mailing list Xen-users@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-users
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