[Qemu-devel] [Bug 979714] Re: The pit interrupt still exists even with tickless guest

[Yongjie Ren]

verified.
this bug should have been fixed by the following commit.

commit 80019541e9c13fab476bee35edcef3e11646222c
Author: Jan Kiszka <address@hidden>
Date:   Mon Apr 23 10:47:14 2012 +0200

    qemu-kvm: Switch to upstream in-kernel KVM PIT

    The upstream version provides the same feature plus proper support for
    the PC speaker port while the in-kernel PIT is enabled.


** Changed in: qemu
       Status: New => Fix Committed

** Changed in: qemu
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/979714

Title:
  The pit interrupt still exists even with tickless guest

Status in QEMU:
  Fix Released

Bug description:
  Environment:
  ------------
  Host OS (ia32/ia32e/IA64):ia32e
  Guest OS (ia32/ia32e/IA64):ia32e
  Guest OS Type (Linux/Windows): Linux(RHEL6u1)
  kvm.git Commit:4f324a1b
  qemu-kvm Commit:  b5ed4b6f 
  Host Kernel Version:3.3.0-rc5
  Hardware: Romley-EP, WSM-EP
  Bug detailed description:
  --------------------------
  Start a guest and check into /proc/interrupts, the timer interrupt will
  constantly increase while local timer interrups are already increasing.
  qemu-kvm commit: 9d636ae7  doesn't have this issue.
  The dmesg of the guest shows:
  APIC calibration not consistent with PM-Timer: 191ms instead of 100ms

  This should be a qemu-kvm bug.
  kvm + qemu-kvm = result
  4f324a1b + b5ed4b6f = bad
  4f324a1b + 9d636ae7 = good
  Reproduce steps:
  ----------------
  1. start up a host with kvm kernel
  2. qemu-system-x86_64 –m 1024 –smp 2 –net none –hda /root/rhel6u1.img
  3. cat /proc/interrupts
  Current result:
  ----------------
  interrupt 0 keeps increasing

  Expected result:
  ----------------
  interrupt 0 stops at some value and doesn't increase

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