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8.2. Hugepage support

Introduction
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 reduce memory consumption and improve performance by reducing CPU cache usage.
By using huge pages for a KVM guest, less memory is used for page tables and TLB (Translation Lookaside Buffer) misses are reduced, thereby significantly increasing performance, especially for memory-intensive situations.
Transparent Hugepage Support 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.
Using Transparent Hugepage Support
To use Transparent Hugepage Support, no special configuration in the qemu.conf file is required. Hugepages are used by default if /sys/kernel/mm/redhat_transparent_hugepage/enabled is set to always.
Transparent Hugepage Support does not prevent the use of hugetlbfs. However, when hugetlbfs is not used, KVM will use transparent hugepages instead of the regular 4kB page size.