[Bug 1914667] [NEW] High cpu usage when guest is idle on qemu-system-i386

[John Arbuckle]

Public bug reported:

When running Windows XP in qemu-system-i386, the cpu usage of QEMU is
about 100% even when the guest CPU usage is close to 2%. The host cpu
usage should be low when the guest cpu usage is low.

Command: qemu-system-i386 -hda <Windows XP HD image>

Using this command also shows around 100% host CPU usage:
qemu-system-i386 -m 700 -hda <Windows XP HD image> -usb -device usb-audio -net 
nic,model=rtl8139 -net user -hdb mountable.img -soundhw pcspk

Using the Penryn CPU option also saw this problem:
qemu-system-i386 -hda <Windows XP HD image> -m 700 -cpu Penryn-v1

Using "-cpu pentium2" saw the same high host cpu usage.


My Info:
M1 MacBook Air
Mac OS 11.1
qemu-system-i386 version 5.2 (1ba089f2255bfdb071be3ce6ac6c3069e8012179)
Windows XP SP3 Build 2600

** Affects: qemu
     Importance: Undecided
         Status: New

** Attachment added: "high cpu usage.png"
   
https://bugs.launchpad.net/bugs/1914667/+attachment/5460096/+files/high%20cpu%20usage.png

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https://bugs.launchpad.net/bugs/1914667

Title:
  High cpu usage when guest is idle on qemu-system-i386

Status in QEMU:
  New

Bug description:
  When running Windows XP in qemu-system-i386, the cpu usage of QEMU is
  about 100% even when the guest CPU usage is close to 2%. The host cpu
  usage should be low when the guest cpu usage is low.

  Command: qemu-system-i386 -hda <Windows XP HD image>

  Using this command also shows around 100% host CPU usage:
  qemu-system-i386 -m 700 -hda <Windows XP HD image> -usb -device usb-audio 
-net nic,model=rtl8139 -net user -hdb mountable.img -soundhw pcspk

  Using the Penryn CPU option also saw this problem:
  qemu-system-i386 -hda <Windows XP HD image> -m 700 -cpu Penryn-v1

  Using "-cpu pentium2" saw the same high host cpu usage.

  
  My Info:
  M1 MacBook Air
  Mac OS 11.1
  qemu-system-i386 version 5.2 (1ba089f2255bfdb071be3ce6ac6c3069e8012179)
  Windows XP SP3 Build 2600

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