clock skew

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clock skew

Gabor HALASZ
Hi!

I experienced a strange clock skew in xen3 (mirrored today, only dom0 run).

With xen:

xen:~# ntpdate 192.168.1.1; sleep 30; ntpdate 192.168.1.1
  7 Nov 18:33:02 ntpdate[3079]: step time server 192.168.1.1 offset
-16.876204 sec
  7 Nov 18:33:11 ntpdate[3085]: step time server 192.168.1.1 offset
-21.131558 sec

Whithout xen (2.6.14-git5):

xen:~# ntpdate 192.168.1.1; sleep 30; ntpdate 192.168.1.1
  7 Nov 18:38:28 ntpdate[481]: adjust time server 192.168.1.1 offset
-0.000100 sec
  7 Nov 18:38:58 ntpdate[487]: adjust time server 192.168.1.1 offset
-0.000095 sec

What can I do?

--
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RE: clock skew

Ian Pratt
 
> I experienced a strange clock skew in xen3 (mirrored today,
> only dom0 run).

This is in a domU, right?
See the "independent_wallclock" parameter.
 
Ian


> With xen:
>
> xen:~# ntpdate 192.168.1.1; sleep 30; ntpdate 192.168.1.1
>   7 Nov 18:33:02 ntpdate[3079]: step time server 192.168.1.1 offset
> -16.876204 sec
>   7 Nov 18:33:11 ntpdate[3085]: step time server 192.168.1.1 offset
> -21.131558 sec
>
> Whithout xen (2.6.14-git5):
>
> xen:~# ntpdate 192.168.1.1; sleep 30; ntpdate 192.168.1.1
>   7 Nov 18:38:28 ntpdate[481]: adjust time server 192.168.1.1 offset
> -0.000100 sec
>   7 Nov 18:38:58 ntpdate[487]: adjust time server 192.168.1.1 offset
> -0.000095 sec
>
> What can I do?
>
> --
> Gabor HALASZ <[hidden email]>
>
> _______________________________________________
> Xen-devel mailing list
> [hidden email]
> http://lists.xensource.com/xen-devel
>

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Re: clock skew

Gabor HALASZ
Ian Pratt wrote:
>  
>
>>I experienced a strange clock skew in xen3 (mirrored today,
>>only dom0 run).
>
>
> This is in a domU, right?

No, this is in dom0 without guests.

xen:~# xm list
Name                              ID Mem(MiB) VCPUs State  Time(s)
Domain-0                           0      245     1 r-----   328.6

> See the "independent_wallclock" parameter.
>  

If I understand the time.c, the independent_wallclock affected on guest
os only? I think, this will not resolv my problem.

--
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RE: clock skew

Ian Pratt
In reply to this post by Gabor HALASZ
 > >>I experienced a strange clock skew in xen3 (mirrored today,
> only dom0
> >>run).

> If I understand the time.c, the independent_wallclock
> affected on guest os only? I think, this will not resolv my problem.

Does time otherwise seem to be progressing normally in your dom0?

What happens if you do:

date; hclock; sleep 60; date; hwclock

ntpdate works fine for me in dom0.

Ian

 

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Re: clock skew

Gabor HALASZ
In reply to this post by Gabor HALASZ
Hi!

I'm here again :( So, Ian Pratt ask me to send this letter to the list
and I'm sorry for a long letter.

My computer is NEC Express5800 120Eg, which contains Intel SE7320SP2 SMP
capable motherboard with one cpu and two giga ram.

xen:~# cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 4
model name      :                   Intel(R) Xeon(TM) CPU 2.80GHz
stepping        : 1
cpu MHz         : 2793.139
cache size      : 1024 KB
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall
lm constant_tsc pni monitor ds_cpl cid cx16 xtpr
bogomips        : 5594.08
clflush size    : 64
cache_alignment : 128
address sizes   : 36 bits physical, 48 bits virtual
power management:

I'm using an Amd64 Debian Sid, the current versions of libc6 and others:

xen:~# gcc -v
Reading specs from /usr/lib/gcc/x86_64-linux-gnu/3.4.5/specs
Configured with: ../src/configure -v
--enable-languages=c,c++,f77,pascal,objc,ada --prefix=/usr
--libexecdir=/usr/lib --with-gxx-include-dir=/usr/include/c++/3.4
--enable-shared --with-system-zlib --enable-nls
--without-included-gettext --program-suffix=-3.4 --enable-__cxa_atexit
--enable-libstdcxx-allocator=mt --enable-clocale=gnu
--enable-libstdcxx-debug x86_64-linux-gnu
Thread model: posix
gcc version 3.4.5 20051015 (prerelease) (Debian 3.4.4-9)
xen:~# cpp -v
Reading specs from /usr/lib/gcc/x86_64-linux-gnu/3.4.5/specs
Configured with: ../src/configure -v
--enable-languages=c,c++,f77,pascal,objc,ada --prefix=/usr
--libexecdir=/usr/lib --with-gxx-include-dir=/usr/include/c++/3.4
--enable-shared --with-system-zlib --enable-nls
--without-included-gettext --program-suffix=-3.4 --enable-__cxa_atexit
--enable-libstdcxx-allocator=mt --enable-clocale=gnu
--enable-libstdcxx-debug x86_64-linux-gnu
Thread model: posix
gcc version 3.4.5 20051015 (prerelease) (Debian 3.4.4-9)
  /usr/lib/gcc/x86_64-linux-gnu/3.4.5/cc1 -E -quiet -v - -mtune=k8
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/include/x86_64-linux-gnu"
#include "..." search starts here:
#include <...> search starts here:
  /usr/local/include
  /usr/lib/gcc/x86_64-linux-gnu/3.4.5/include
  /usr/include
End of search list.

The first test without xen seems to be good (this kernel compiled on
this machine):

xen:~# uname -a
Linux xen 2.6.14.1-x8664-ump #1 Thu Nov 10 14:12:03 CET 2005 x86_64
GNU/Linux
xen:~# date; hwclock; sleep 60; date; hwclock;
Thu Nov 10 15:09:01 CET 2005
Thu 10 Nov 2005 03:09:02 PM CET  -0.191327 seconds
Thu Nov 10 15:10:01 CET 2005
Thu 10 Nov 2005 03:10:03 PM CET  -0.989809 seconds

I updated xen today and built from scratch:

xen:/usr/src/xen/xen-devel# hg parents
changeset:   7713:136b2d20dc81
tag:         tip
user:        [hidden email]
date:        Wed Nov  9 16:08:37 2005 +0100
summary:     Cope with the ValueError exception that we get if you use
Xend with the recent

After this I boot the xen kernel (dom0 only) and I experienced a strange
clock skew again.

xen:~# date; hwclock; sleep 120; date; hwclock;
Thu Nov 10 16:27:31 CET 2005
Thu 10 Nov 2005 04:21:00 PM CET  -1.676444 seconds
Thu Nov 10 16:29:32 CET 2005
Thu 10 Nov 2005 04:21:37 PM CET  -3.299808 seconds

Yes, this was only 37s, not 120s!!
I tried this in domU and I got same result.


xen:~# xm dmesg
  __  __            _____  ___         _                _
  \ \/ /___ _ __   |___ / / _ \     __| | _____   _____| |
   \  // _ \ '_ \    |_ \| | | |__ / _` |/ _ \ \ / / _ \ |
   /  \  __/ | | |  ___) | |_| |__| (_| |  __/\ V /  __/ |
  /_/\_\___|_| |_| |____(_)___/    \__,_|\___| \_/ \___|_|

  http://www.cl.cam.ac.uk/netos/xen
  University of Cambridge Computer Laboratory

  Xen version 3.0-devel (root@) (gcc version 3.4.5 20051015 (prerelease)
(Debian
3.4.4-9)) Thu Nov 10 15:36:48 CET 2005
  Latest ChangeSet: Wed Nov  9 16:08:37 2005 +0100 7713:136b2d20dc81

(XEN) Physical RAM map:
(XEN)  0000000000000000 - 000000000009a800 (usable)
(XEN)  000000000009a800 - 00000000000a0000 (reserved)
(XEN)  00000000000e0000 - 0000000000100000 (reserved)
(XEN)  0000000000100000 - 000000007ffddf12 (usable)
(XEN)  000000007ffddf12 - 000000007fff0000 (reserved)
(XEN)  000000007fff0000 - 000000007ffff000 (ACPI data)
(XEN)  000000007ffff000 - 0000000080000000 (ACPI NVS)
(XEN)  00000000fec00000 - 00000000fec86000 (reserved)
(XEN)  00000000fee00000 - 00000000fee01000 (reserved)
(XEN)  00000000ffc00000 - 0000000100000000 (reserved)
(XEN) System RAM: 2047MB (2096604kB)
(XEN) Xen heap: 14MB (14648kB)
(XEN) found SMP MP-table at 000ff780
(XEN) DMI 2.3 present.
(XEN) Using APIC driver default
(XEN) ACPI: RSDP (v000 ACPIAM                                ) @
0x00000000000f7
9e0
(XEN) ACPI: RSDT (v001 A M I  OEMRSDT  0x04000522 MSFT 0x00000097) @
0x000000007
fff0000
(XEN) ACPI: FADT (v001 A M I  OEMFACP  0x04000522 MSFT 0x00000097) @
0x000000007
fff0200
(XEN) ACPI: MADT (v001 A M I  OEMAPIC  0x04000522 MSFT 0x00000097) @
0x000000007
fff0300
(XEN) ACPI: MCFG (v001 A M I  OEMMCFG  0x04000522 MSFT 0x00000097) @
0x000000007
fff03e0
(XEN) ACPI: OEMB (v001 A M I  OEMBIOS  0x04000522 MSFT 0x00000097) @
0x000000007
ffff040
(XEN) ACPI: DSDT (v001  LHREF LHREF081 0x00000081 INTL 0x02002026) @
0x000000000
0000000
(XEN) ACPI: Local APIC address 0xfee00000
(XEN) ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled)
(XEN) Processor #0 15:4 APIC version 20
(XEN) ACPI: LAPIC (acpi_id[0x02] lapic_id[0x01] enabled)
(XEN) Processor #1 15:4 APIC version 20
(XEN) ACPI: LAPIC (acpi_id[0x03] lapic_id[0x82] disabled)
(XEN) ACPI: LAPIC (acpi_id[0x04] lapic_id[0x83] disabled)
(XEN) ACPI: LAPIC_NMI (acpi_id[0x01] high edge lint[0x1])
(XEN) ACPI: LAPIC_NMI (acpi_id[0x02] high edge lint[0x1])
(XEN) ACPI: LAPIC_NMI (acpi_id[0x03] high edge lint[0x1])
(XEN) ACPI: LAPIC_NMI (acpi_id[0x04] high edge lint[0x1])
(XEN) ACPI: IOAPIC (id[0x02] address[0xfec00000] gsi_base[0])
(XEN) IOAPIC[0]: apic_id 2, version 32, address 0xfec00000, GSI 0-23
(XEN) ACPI: IOAPIC (id[0x03] address[0xfec10000] gsi_base[24])
(XEN) IOAPIC[1]: apic_id 3, version 32, address 0xfec10000, GSI 24-47
(XEN) ACPI: INT_SRC_OVR (bus 0 bus_irq 0 global_irq 2 dfl dfl)
(XEN) ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 high level)
(XEN) ACPI: IRQ0 used by override.
(XEN) ACPI: IRQ2 used by override.
(XEN) ACPI: IRQ9 used by override.
(XEN) Enabling APIC mode:  Flat.  Using 2 I/O APICs
(XEN) Using ACPI (MADT) for SMP configuration information
(XEN) Initializing CPU#0
(XEN) Detected 2793.141 MHz processor.
(XEN) Using scheduler: Simple EDF Scheduler (sedf)
(XEN) CPU: Trace cache: 12K uops, L1 D cache: 16K
(XEN) CPU: L2 cache: 1024K
(XEN) CPU: Physical Processor ID: 0
(XEN) CPU0: Intel(R) Xeon(TM) CPU 2.80GHz stepping 01
(XEN) Booting processor 1/1 eip 90000
(XEN) Initializing CPU#1
(XEN) CPU: Trace cache: 12K uops, L1 D cache: 16K
(XEN) CPU: L2 cache: 1024K
(XEN) CPU: Physical Processor ID: 0
(XEN) CPU1: Intel(R) Xeon(TM) CPU 2.80GHz stepping 01
(XEN) Total of 2 processors activated.
(XEN) ENABLING IO-APIC IRQs
(XEN) ..TIMER: vector=0x31 pin1=2 pin2=-1
(XEN) checking TSC synchronization across 2 CPUs: passed.
(XEN) Platform timer is 1.193MHz PIT
(XEN) Brought up 2 CPUs
(XEN) mtrr: v2.0 (20020519)
(XEN) *** LOADING DOMAIN 0 ***
(XEN) Xen-ELF header found:
'GUEST_OS=linux,GUEST_VER=2.6,XEN_VER=3.0,VIRT_BASE=
0xffffffff80000000,LOADER=generic'
(XEN) PHYSICAL MEMORY ARRANGEMENT:
(XEN)  Dom0 alloc.:   0000000078000000->000000007c000000 (47652 pages to
be allo
cated)
(XEN) VIRTUAL MEMORY ARRANGEMENT:
(XEN)  Loaded kernel: ffffffff80100000->ffffffff8035a086
(XEN)  Init. ramdisk: ffffffff8035b000->ffffffff8235b000
(XEN)  Phys-Mach map: ffffffff8235b000->ffffffff823d8120
(XEN)  Start info:    ffffffff823d9000->ffffffff823da000
(XEN)  Page tables:   ffffffff823da000->ffffffff823f1000
(XEN)  Boot stack:    ffffffff823f1000->ffffffff823f2000
(XEN)  TOTAL:         ffffffff80000000->ffffffff82800000
(XEN)  ENTRY ADDRESS: ffffffff80100000
(XEN) Initrd len 0x2000000, start at 0xffffffff8035b000
(XEN) Scrubbing Free RAM: .....................done.
(XEN) Xen trace buffers: disabled
(XEN) *** Serial input -> DOM0 (type 'CTRL-a' three times to switch
input to Xen
).


My kernel config:

  CONFIG_XEN=y
  CONFIG_ARCH_XEN=y
@@ -17,9 +17,8 @@
  CONFIG_XEN_NETDEV_BACKEND=y
  # CONFIG_XEN_TPMDEV_FRONTEND is not set
  # CONFIG_XEN_TPMDEV_BACKEND is not set
-CONFIG_XEN_BLKDEV_FRONTEND=y
-CONFIG_XEN_NETDEV_FRONTEND=y
-# CONFIG_XEN_NETDEV_FRONTEND_PIPELINED_TRANSMITTER is not set
+# CONFIG_XEN_BLKDEV_FRONTEND is not set
+# CONFIG_XEN_NETDEV_FRONTEND is not set
  # CONFIG_XEN_BLKDEV_TAP is not set
  # CONFIG_XEN_SHADOW_MODE is not set
  CONFIG_XEN_SCRUB_PAGES=y
@@ -32,8 +31,7 @@
  # Code maturity level options
  #
  CONFIG_EXPERIMENTAL=y
-# CONFIG_CLEAN_COMPILE is not set
-CONFIG_BROKEN=y
+CONFIG_CLEAN_COMPILE=y
  CONFIG_BROKEN_ON_SMP=y
  CONFIG_INIT_ENV_ARG_LIMIT=32

@@ -43,10 +41,12 @@
  CONFIG_LOCALVERSION=""
  CONFIG_SWAP=y
  CONFIG_SYSVIPC=y
-# CONFIG_POSIX_MQUEUE is not set
-# CONFIG_BSD_PROCESS_ACCT is not set
+CONFIG_POSIX_MQUEUE=y
+CONFIG_BSD_PROCESS_ACCT=y
+CONFIG_BSD_PROCESS_ACCT_V3=y
  CONFIG_SYSCTL=y
-# CONFIG_AUDIT is not set
+CONFIG_AUDIT=y
+CONFIG_AUDITSYSCALL=y
  CONFIG_HOTPLUG=y
  CONFIG_KOBJECT_UEVENT=y
  # CONFIG_IKCONFIG is not set
@@ -72,15 +72,14 @@
  #
  CONFIG_MODULES=y
  CONFIG_MODULE_UNLOAD=y
-# CONFIG_MODULE_FORCE_UNLOAD is not set
+CONFIG_MODULE_FORCE_UNLOAD=y
  CONFIG_OBSOLETE_MODPARM=y
  # CONFIG_MODVERSIONS is not set
-# CONFIG_MODULE_SRCVERSION_ALL is not set
+CONFIG_MODULE_SRCVERSION_ALL=y
  CONFIG_KMOD=y
  CONFIG_XENARCH="x86_64"
  CONFIG_X86=y
  CONFIG_MMU=y
-CONFIG_UID16=y
  CONFIG_GENERIC_ISA_DMA=y
  CONFIG_GENERIC_IOMAP=y
  CONFIG_X86_CMPXCHG=y
@@ -91,7 +90,7 @@
  # CONFIG_HPET_TIMER is not set
  # CONFIG_SMP is not set
  # CONFIG_PREEMPT is not set
-CONFIG_MICROCODE=y
+# CONFIG_MICROCODE is not set
  # CONFIG_X86_CPUID is not set
  CONFIG_SWIOTLB=y
  # CONFIG_NUMA is not set
@@ -100,7 +99,7 @@
  CONFIG_X86_IO_APIC=y
  CONFIG_PCI=y
  CONFIG_PCI_DIRECT=y
-# CONFIG_PCI_MMCONFIG is not set
+CONFIG_PCI_MMCONFIG=y
  CONFIG_ISA_DMA_API=y
  CONFIG_GENERIC_HARDIRQS=y
  CONFIG_GENERIC_IRQ_PROBE=y
@@ -139,21 +138,18 @@
  #
  # Bus options (PCI etc.)
  #
-# CONFIG_UNORDERED_IO is not set
+CONFIG_UNORDERED_IO=y

  #
  # Executable file formats / Emulations
  #
-CONFIG_IA32_EMULATION=y
-# CONFIG_IA32_AOUT is not set
-CONFIG_COMPAT=y
-CONFIG_SYSVIPC_COMPAT=y
+# CONFIG_IA32_EMULATION is not set

  #
  # Executable file formats
  #
  CONFIG_BINFMT_ELF=y
-CONFIG_BINFMT_MISC=y
+CONFIG_BINFMT_MISC=m

....




--
Gabor HALASZ <[hidden email]>

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