How a Hypervisor Actually Shares CPU and I/O: A Practical Guide for KVM, LXC and Proxmox
vCPUs are just threads, cgroups don't replace the scheduler, and on NVMe the right I/O scheduler is usually 'none'. A ground-up tour of how Linux shares physical resources between virtual machines and containers — and which knobs are actually worth turning for small-to-medium workloads.