KVM - vhost-net vs Userspace Host CPU Performance Comparison
I've been kicking the tires recently on a new KVM server I'm using for a home lab, and one of the things I've been investigating recently is network optimization in the guest.
Being especially anal about it and during my investigation of whether or not I could reasonably fix an approximately 500usec latency difference between pinging the guest and host, I started to look into making sure vhost-net was enabled on my rudimentary and extremely minimal KVM host running Alpine Linux. After ultimately getting it set up and finding the same latency, I wanted to see where the real value laid with having this setup on what will ultimately still be a not-so-busy low-end machine. I found some interesting results!
TL;DR: at the very least, vhost-net will save you a decent amount of CPU. Read on!