Xen Huge Pages
- Huge pages is also known as superpages in FreeBSD, and large pages in Microsoft Windows terminology.
- Newer AMD64 processors can use 1GB pages in long mode.
- Linux has supported huge pages on several architectures since the 2.6 series via the hugetlbfs filesystem.
- Xen supports allocating huge pages for guest. Itself doesn't use huge pages.
Specify the hypervisor boot command line flag allowsuperpage (it was called allowhugepage before).
Create the VM with option superpages = 1.
This option is for PV guest only; it has no effect to HVM guest.
With this option, PV guest memory and maxmem must be 2M aligned. Otherwise the VM cannot be started.
Specify the Linux boot command line flag balloon_hugepages.
In the guest:
# echo 20 > /proc/sys/vm/nr_hugepages # cat /proc/meminfo ... AnonHugePages: 0 kB HugePages_Total: 20 HugePages_Free: 20 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 1056768 kB DirectMap2M: 0 kB