Hardware Virtual Machine: An approach to get bare metal performance

Introduction

Laymen explanation

If you are looking for high performance VM, you may look for the hardware support. For example, a high performance network VM will need feature which increases throughput drastically. SR-IOV is one such feature for this.

Similarly, for high speed I/O in DBMS, you will need hardware support. HVM helps in this regard

Technical explanation

HVM (known as Hardware Virtual Machine) is the type of instance that mimics bare-metal server setup which provides better hardware isolation. With this instance type, the OS can run directly on top of the Virtual Machine without additional configuration making it to look like it is running on a real physical server.

Xen HVM

Fully virtualized aka HVM (Hardware Virtual Machine) guests require CPU virtualization extensions from the host CPU (Intel VT, AMD-V). Xen uses modified version of Qemu to emulate full PC hardware, including BIOS, IDE disk controller, VGA graphic adapter, USB controller, network adapter etc for HVM guests. CPU virtualization extensions are used to boost performance of the emulation.

Infra requirement

HVM requires Intel VT or AMD-V hardware extensions for memory and privileged operations.

Production softwares which recommends HVM

Neo4J

Quote

"We recommend choosing HVM (hardware virtual machine) instances. HVM instances perform slightly better for our workloads than the old paravirtual instances. "

Refer: https://neo4j.com/blog/graphs-to-production-at-scale/

SR-IOV networking

Quote

"Virtual machines must be HVM guest."

Refer: https://support.citrix.com/article/CTX235044

DPDK

sudo virt-install –connect qemu:///system -n vm2 -r 1024 –vcpus=3 –disk path=/var/lib/libvirt/images/vm2.img,size=12 -c /home/ubuntu/images/ubuntu-14.04.1-server-amd64.iso –noautoconsole –os-type linux –accelerate –network=bridge:virbr0 –hvm –graphics vnc,listen=0.0.0.0 –cpu host

Refer: https://haryachyy.wordpress.com/2014/11/09/learning-dpdk-l2-forwarding-app-in-vm/

AWS instance recommendation

Quote

"We recommend using HVM AMIs for improved performance. HVM AMIs also offer newer instance classes (for example, M5, M4, and R4) and Amazon EC2 features such as enhanced networking. For more information, see Linux AMI Virtualization Types."

Refer: https://aws.amazon.com/premiumsupport/knowledge-center/ec2-linux-performance/

Reference

https://docs.rightscale.com/faq/What_is_Hardware_Virtual_Machine_or_HVM.html

https://serverfault.com/questions/222010/difference-between-xen-pv-xen-kvm-and-hvm

https://docs.citrix.com/en-us/citrix-hypervisor/technical-overview.html