OS and Hypervisor Vendors : Technical Documentation
Red Hat
Red Hat Enterprise Linux 7 Performance Tuning Guide
SUSE
Deployment Guide: SUSE Linux Enterprise Server 12 SP3
Virtualization Guide: SUSE Linux Enterprise Server 12 SP3
Virtualization Best Practices: SUSE Linux Enterprise Server 12 SP3
Canonical
Ubuntu Server Guide: Virtualization
VMware
Performance Best Practices for VMware vSphere 6.5
Citrix