Re: [libvirt] Problem with setting up KVM guests to use HugePages

Configure hugepages and then start virtual guest via "virsh start". However, virtual guest failed to use hugepages although it's configured The initial usage of system memory [root@local ~]# free total used free shared buff/cache available Mem: 263767352 1900628 261177892 9344 688832 261431872 Swap: 4194300 0 4194300 After configuring hugepages, [root@local ~]# cat /proc/meminfo | grep uge AnonHugePages: 2048 kB HugePages_Total: 140 HugePages_Free: 140 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 1048576 kB [root@local ~]# mount | grep huge cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec, relatime,hugetlb)hugetlbfs on /dev/hugepages type hugetlbfs (rw,realtime) On the guest side, its config xml contains <domain type='kvm'> <name>test-01</name> <uuid>e1b72349-4a0b-4b91-aedc-fd34e92251e4</uuid> <description>test-01</description> <memory unit='KiB'>134217728</memory> <currentMemory unit='KiB'>134217728</currentMemory> <memoryBacking> <hugepages/>

<nosharepages/> </memoryBacking> Tried to virsh start the guest, but it failed although the hugepages memory was sufficient virsh # start test-01 error: Failed to start domain test-01 error: internal error: early end of file from monitor: possible problem: Cannot set up guest memory 'pc.ram': Cannot allocate memory however, if decrease the number of hugepages to smaller(say 100) that makes the memory not used by hugepages more than required by guest, then guest can start. But memory is not allocated from hugepages. [root@local ~]# cat /proc/meminfo | grep uge AnonHugePages: 134254592 kB HugePages_Total: 100 HugePages_Free: 100 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 1048576 kB In summary, although hugepages is configured, the guest seemed not instructed to use hugepage, instead, the guest is allocated memory from the memory pool leftover by hugepages. -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list