Virtualization (虚拟化)
Types of Hypervisor
| Types | Hypervisors | Technologies |
|---|---|---|
| Type-1 | native or bare-metal | KVM, Xen, Microsoft Hyper-V, VMware ESXi |
| Type-2 | hosted | VMware Workstation, Oracle VirtualBox |
Virtualization with Linux
| - | KVM | Xen |
|---|---|---|
| Start Year | 2007, Linux 2.6.20+ | 2003 |
| Future Direction | Server Virtualization | Desktop Virtualization |
| Cloud Service | AWS (2017+): C5+, Alibaba Cloud (阿里云), Tencent Cloud (腾讯云) | Oracle Cloud, IBM Softlayer |
KVM (Kernel-based VM)
Advantage
- Reuse hardware virtualization technologies (hardware-assistant virtualization), such as Intel VT and AMD-V.
- Reuse software (kernel) virtualization technologies: vCPU, memory management, process schedule, I/O controller, device drivers, networking controllers.
vCPU Modes
| - | User Mode | Kernel Mode | Guest Mode |
|---|---|---|---|
| running | QEMU | KVM kernel module | Guest OS |
| virtualize | I/O: networking and disk storage | CPU and memory | - |
Memory Virtualization
- Address Mapping
- Intel EPT (Extend Page Table)
- AMD NPT (Nested Page Table).
- TLB (Translation Lookaside Buffer)
- Intel VPID (Virtual-Processor Identifier)
- THP (Transparent Hugepage)
- Over-Commit (内存超分)
- Swapping (内存交换)
- Ballooning (气球):
virtio_balloondriver - Page Sharing (页共享): KSM (Kernel Samepage Merging)