* fengyd (fengy...@gmail.com) wrote: > Hi, > > During live migration, the folloing log can see in nova-compute.log in my > environment: > ERROR nova.virt.libvirt.driver [req-039a85e1-e7a1-4a63-bc6d-c4b9a044aab6 > 0cdab20dc79f4bc6ae5790e7b4a898ac 3363c319773549178acc67f32c78310e - default > default] [instance: 5ec719f4-1865-4afe-a207-3d9fae22c410] Live Migration > failure: internal error: qemu unexpectedly closed the monitor: > 2019-04-15T02:58:22.213897Z qemu-kvm: VQ 0 > size 0x100 < last_avail_idx 0x1e - used_idx 0x23 > > It's OK for standard Linux VM, but not OK for our VM where virtio is > implemented by ourself. > KVM version as follow: > qemu-kvm-common-ev-2.12.0-18.el7_6.3.1.x86_64 > qemu-kvm-ev-2.12.0-18.el7_6.3.1.x86_64 > libvirt-daemon-kvm-3.9.0-14.2.el7.centos.ncir.8.x86_64 > > Do you know what's the difference between virtio and vhost-user during > migration? > The function virtio_load in Qemu is called for virtio and vhost-user during > migration. > For virtio, last_avail_idx and used_idx are stored in Qemu, Qemu is > responsible for updating their values accordingly > For vhost-user, last_avail_idx and used_idx are stored in vhost-user app, > eg. DPDK, not in Qemu? > How does migration work for vhost-user?
I don't know the details, but my understanding is that vhost-user tells the vhost-user client about an area of 'log' memory, where the vhost-user client must mark pages as dirty. In the qemu source, see docs/interop/vhost-user.txt and see the VHOST_SET_LOG_BASE and VHOST_USER_SET_LOG_FD calls. If the client correctly marks the areas as dirty, then qemu should resend those pages across. Dave > Thanks in advance > Yafeng -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
