Public bug reported: In previous releases (tested with Saucy), if one wanted to use hugetlbfs for a VM, the needed procedure was:
1) Add "vm.nr_hugepages" to /etc/sysctl.d/60-hugepages.conf 2) start procps 3) Set KVM_HUGEPAGES=1 in /etc/default/qemu-kvm 4) restart qemu-kvm 5) Enable "<memoryBacking> <hugepages/></memoryBacking>" in the libvirt guest definition 6) Restart the guest Now with Trusty, this doesn't work anymore as there is no (obvious?) way to have the hugetlbfs mounted where QEMU expects it. On Saucy, the upstart job for qemu-kvm contains this: # mount hugepages if available and requested if [ "$KVM_HUGEPAGES" -eq "1" ]; then if ! grep -q hugetlbfs /proc/filesystems; then logger -t qemu-kvm "Error: hugepages not available in the kernel!" elif grep -q /run/hugepages/kvm /proc/mounts; then logger -t qemu-kvm "/run/hugepages/kvm already mounted" elif ! grep -q kvm /etc/group; then logger -t qemu-kvm "Error: group kvm does not exist!" else kvmgid=`grep kvm /etc/group | cut -d: -f 3` mkdir -p /run/hugepages/kvm mount -t hugetlbfs hugetlbfs-kvm -o mode=775,gid=$kvmgid /run/hugepages/kvm fi fi But it seems there is nothing similar in Trusty and manually mounting the hugetlbfs doesn't help as qemu cannot find it there. Host information: $ lsb_release -rd Description: Ubuntu 14.04 LTS Release: 14.04 $ apt-cache policy qemu-system-x86 libvirt-bin qemu-system-x86: Installed: 2.0.0+dfsg-2ubuntu1 Candidate: 2.0.0+dfsg-2ubuntu1 Version table: *** 2.0.0+dfsg-2ubuntu1 0 500 http://archive.ubuntu.com/ubuntu/ trusty-proposed/main amd64 Packages 100 /var/lib/dpkg/status 2.0.0~rc1+dfsg-0ubuntu3.1 0 500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages 500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages 2.0.0~rc1+dfsg-0ubuntu3 0 500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages libvirt-bin: Installed: 1.2.2-0ubuntu13.1 Candidate: 1.2.2-0ubuntu13.1 Version table: *** 1.2.2-0ubuntu13.1 0 500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages 100 /var/lib/dpkg/status 1.2.2-0ubuntu13 0 500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: qemu-system-common 2.0.0+dfsg-2ubuntu1 ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9 Uname: Linux 3.13.0-24-generic x86_64 ApportVersion: 2.14.1-0ubuntu3 Architecture: amd64 CurrentDesktop: Unity Date: Fri May 2 10:05:18 2014 InstallationDate: Installed on 2014-01-26 (95 days ago) InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140124) SourcePackage: qemu UpgradeStatus: No upgrade log present (probably fresh install) ** Affects: qemu (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug package-from-proposed trusty -- You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to qemu in Ubuntu. https://bugs.launchpad.net/bugs/1315402 Title: No easy way to use hugetlbfs with QEMU To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/qemu/+bug/1315402/+subscriptions -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs