Xen配置文件中hap选项

Xen配置文件中hap选项

Tuning Xen for Performance

hap=0：虚拟机使用影子模式

hap=1：虚拟机使用EPT模式

HAP stands for hardware assisted paging and requires a CPU feature called EPT by Intel and RVI by AMD. It is used to manage the guest’s MMU. The alternative is shadow paging, completely managed in software by Xen. On HAP TLB misses are expensive so if you have really random access, HAP will be expensive. On shadow page table updates are expensive. HAP is enabled by default (and it is the recommended setting) but can be disabled passing hap=0 in the VM config file.

这个选项主要是选择影子页表模式还是EPT模式。

本人主要使用了这两种在处理虚拟机缺页处理时的不同。

KVM 内存虚拟化及其实现

intel EPT 机制详解

本人的使用环境需要虚拟客户机产生缺页异常时执行VMExit进入到Hypervisor层，因此需要使用影子页表模式。