Why qemu-system-x86 takes 100% of my CPU?

kvm openstack qemu openstack-autopilot

23,515

Have you tried to make sure you use the proper accelaration for qemu?
Such as:

qemu-system-x86_64  -machine accel=kvm [...]

This switch could make your computer use hardware virtualization
(cpu usage drops to negligible then)

23,515

Riccardo Magrini

Network & Security/Firewall Engineer with over 5+ years experience in Information Technology, networking and security dept. Good knowledge of L2 and L3 network devices (Cisco Switch/Router device, IBM devices, Wildix VoIP PBX, Palo Alto and FortiGate Next-Generation Firewall) for data center network and LAN/WAN infrastructure. Experience in plan/design network and virtualization environment with VMware vCloud Suite (VMware Datacenter & Cloud Infrastructure), KVM Hypervisor, MaaS, Juju and IaaS cloud infrastructure (Openstack base knowledge). I have obtained the CCNA 640-802 Certification (Cisco Certified Network Associate Routing & Switching) and one year later also the CCNP certification (Cisco Certified Network Professional Routing & Switching). Actually I’m preparing the CCNA 640-911, 640-916 certification (Cisco Certified Network Associate Data Center). I've just passed the Palo Alto Networks ACE exam and obtained the Accredited Configuration Engineer Certification. My personal goal is to become an expert of Data Center Network, Storage Area Network (SAN), Security Area and Virtualization environment.

Updated on September 18, 2022

Comments

Riccardo Magrini over 1 year
I've changed my old laptop with a new one but I don't understand why using on both virt-manager the qemu-system-x86 on new one takes 100% of CPU when run a vm, while on old one not.

The command:

lscpu

has this output:
```
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    2
Core(s) per socket:    2
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 69
Stepping:              1
CPU MHz:               754.000
BogoMIPS:              5187.74
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              4096K
NUMA node0 CPU(s):     0-3
```
While in my old PC it just uses 15%-30% of the CPU. I've also actived the kvm from the BIOS but nothing changes: it continues to use 100%.

The top command gives me:
```
PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
3410 libvirt+  20   0 3641892 902428  10332 S 101,4 11,2   1:03.36 qemu-system-x86
```
How should I proceed?
- saiarcot895 over 9 years
  
  This indicates that you have some VM running, although I don't know why it would be starting automatically at startup. Running ps aux | grep qemu-system-x86 will give you the full arguments for the process.
- Riccardo Magrini over 9 years
  
  the result of that command is that paste.ubuntu.com/9625324
- saiarcot895 over 9 years
  
  There's a VM named CanonicalDistibution running, with a storage file at /home/d4rkn3t/VStorage/CanonicalDistibution.img. You can install the virt-manager to get a GUI (Virtual Machine Manager) so that you can stop or delete the VM.
- Riccardo Magrini over 9 years
  
  VM already run on virtual-manager. I don't understand why in my old PC I never saw virt-manager token 100% of ram, while in new one the result is that?
- saiarcot895 over 9 years
  
  Don't know about that. Is it possible you used some special ISO in installing Ubuntu in the new laptop?
- Riccardo Magrini over 9 years
  
  Ubuntu 14.04Lts 64bit that's it
Zeshan B almost 9 years

hi, can you tell us what did you modify on bios?
pmiranda over 3 years

What option was that?...