8.2. Huge Page Support
x86 CPUs usually address memory in 4kB pages, but they are capable of using larger pages known as huge pages. KVM guests can be deployed with huge page memory support in order to improve performance by increasing CPU cache hits against the Transaction Lookaside Buffer (TLB). Huge pages can significantly increase performance, particularly for large memory and memory-intensive workloads. Red Hat Enterprise Linux 6 is able to more effectively manage large amounts of memory by increasing the page size through the use of huge pages.
Transparent huge pages (THP) is a kernel feature that reduces TLB entries needed for an application. By also allowing all free memory to be used as cache, performance is increased.
qemu.conffile is required. Huge pages are used by default if
/sys/kernel/mm/redhat_transparent_hugepage/enabledis set to always.
hugetlbfsfeature. However, when hugetlbfs is not used, KVM will use transparent huge pages instead of the regular 4kB page size.