[Qemu-devel] [Bug 1086782] Re: HPET time drift windows 7 64bits guest

[Thomas Huth]

Triaging old bug tickets... can you still reproduce this issue with the
latest version of QEMU? Or could we close this ticket nowadays?

** Changed in: qemu
       Status: New => Incomplete

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Title:
  HPET time drift windows 7 64bits guest

Status in QEMU:
  Incomplete

Bug description:
  Using latest qemu-kvm (1.2.0), time drift (clock slow in guest) in Windows 7 
64 bits guest when HPET is enabled (default).
  Disabling HPET (-no-hpet) solves the time drift.

  UsePlatformClock enable/disable doesn't make a difference in the guest.
  bcdedit /set useplatformclock true

  Using driftfix slew doesn't make a difference too.

  
  # qemu-system-x86_64 --version
  QEMU emulator version 1.2.0 (qemu-kvm-1.2.0), Copyright (c) 2003-2008 Fabrice 
Bellard

  Kernel is 3.6.8:
  # uname -a
  Linux pulsar 3.6.8 #1 SMP Sat Dec 1 16:26:10 CET 2012 x86_64 x86_64 x86_64 
GNU/Linux

  TSC is stable in the host:
  ===
  # cat /sys/devices/system/clocksource/clocksource0/current_clocksource
  tsc

  Dmesg:
  [    0.000000] hpet clockevent registered
  [    0.000000] tsc: Fast TSC calibration using PIT
  [    0.000000] tsc: Detected 2660.096 MHz processor
  [    0.001002] Calibrating delay loop (skipped), value calculated using timer 
frequency.. 5320.19 BogoMIPS (lpj=2660096)
  [    0.001138] pid_max: default: 32768 minimum: 301
  ...
  [    1.492019] tsc: Refined TSC clocksource calibration: 2659.973 MHz
  [    1.492093] Switching to clocksource tsc

  
  CPUinfo, constant_tsc:
  vendor_id       : GenuineIntel
  cpu family      : 6
  model           : 23
  model name      : Intel(R) Core(TM)2 Quad CPU    Q8400  @ 2.66GHz
  stepping        : 10
  microcode       : 0xa0b
  cpu MHz         : 2667.000
  cache size      : 2048 KB
  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 pbe syscall nx lm 
constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor 
ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm sse4_1 xsave lahf_lm dtherm tpr_shadow 
vnmi flexpriority
  bogomips        : 5320.19

  # grep -i hpet .config
  CONFIG_HPET_TIMER=y
  CONFIG_HPET_EMULATE_RTC=y
  CONFIG_HPET=y
  # CONFIG_HPET_MMAP is not set
  ===

  Qemu command line:
  /usr/bin/qemu-system-x86_64 -drive 
file=/dev/vol0/KVMORION01,cache=none,aio=native,if=virtio \
    -drive file=/dev/vol0/KVMORION02,cache=none,aio=native,if=virtio \
    -cpu host \
    -m 2048 \
    -smp 4,maxcpus=4,cores=4,threads=1,sockets=1 \
    -rtc base=localtime,driftfix=slew \
    -vnc 10.124.241.211:0,password -k es \
    -monitor telnet:localhost:37200,server,nowait \
    -netdev 
tap,id=kvmorion,ifname=kvmorion,script=/etc/qemu-ifup-br0,downscript=/etc/qemu-ifdown-br0
 \
    -device virtio-net-pci,netdev=kvmorion,id=virtio-nic0,mac=02:85:64:02:c2:aa 
\
    -device virtio-balloon-pci,id=balloon0 \
    -boot menu=on \
    -pidfile /var/run/kvmorion.pid \
    -daemonize

  Using 1 CPU doesn't make a difference.
  Only workaround is disabling hpet (-no-hpet)

  Sample time drift in guest:
  >ntpdate -q 10.124.241.211
   5 Dec 13:36:06 ntpdate[3464]: Raised to realtime priority class
  server 10.124.241.211, stratum 2, offset 3.694184, delay 0.02551
   5 Dec 13:36:12 ntpdate[3464]: step time server 10.124.241.211 offset 
3.694184 s
  ec

  >ntpdate -q 10.124.241.211
   5 Dec 13:52:02 ntpdate[1964]: Raised to realtime priority class
  server 10.124.241.211, stratum 2, offset 4.719968, delay 0.02554
   5 Dec 13:52:08 ntpdate[1964]: step time server 10.124.241.211 offset 
4.719968 s
  ec

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