8.3.3.2. Configuring Static Huge Pages

Procedure 8.1. Setting huge pages

1. View the current huge pages value:

   # cat /proc/meminfo | grep Huge
   AnonHugePages:      2048 kB
   HugePages_Total:       0
   HugePages_Free:        0
   HugePages_Rsvd:        0
   HugePages_Surp:        0
   Hugepagesize:       2048 kB

2. Huge pages are set in increments of 2MB. To set the number of huge pages to 25000, use the following command:

   echo 25000 > /proc/sys/vm/nr_hugepages

   Note

   To make the setting persistent, add the following lines to the /etc/sysctl.conf file on the guest machine, with X being the intended number of huge pages:

   # echo 'vm.nr_hugepages = X' >> /etc/sysctl.conf
   # sysctl -p
   

   Afterwards, add transparent_hugepage=never to the kernel boot parameters by appending it to the end of the /kernel line in the /etc/grub2.cfg file on the guest.
3. Mount the huge pages:

   # mount -t hugetlbfs hugetlbfs /dev/hugepages

4. Restart libvirtd, then restart the virtual machine:

   # service libvirtd restart
   Stopping libvirtd daemon:                                  [  OK ]
   Starting libvirtd daemon:                                  [  OK ]

   # virsh start virtual_machine

5. Verify the changes in /proc/meminfo:

   # cat /proc/meminfo | grep Huge
   AnonHugePages:         0 kB
   HugePages_Total:   25000
   HugePages_Free:    23425
   HugePages_Rsvd:        0
   HugePages_Surp:        0
   Hugepagesize:       2048 kB