* fengyd (fengy...@gmail.com) wrote: > ---------- Forwarded message --------- > From: fengyd <fengy...@gmail.com> > Date: Tue, 16 Apr 2019 at 09:17 > Subject: Re: [Qemu-devel] How live migration work for vhost-user > To: Dr. David Alan Gilbert <dgilb...@redhat.com> > > > Hi, > > Any special feature needs to be supported on guest driver? > Because it's OK for standard Linux VM, but not OK for our VM where virtio > is implemented by ourself.
I'm not sure; you do have to support that 'log' mechanism but I don't know what else is needed. > And with qemu-kvm-ev-2.6, live migration can work with our VM where virtio > is implemented by ourself. 2.6 is pretty old, so there's a lot of changes - not sure what's relevant. Dave > Thanks > Yafeng > > On Mon, 15 Apr 2019 at 22:54, Dr. David Alan Gilbert <dgilb...@redhat.com> > wrote: > > > * 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 > > -- Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
