|
|
| (One intermediate revision by one other user not shown) |
| Line 4: |
Line 4: |
| * Virtio was chosen to be the main platform for IO virtualization in KVM | | * Virtio was chosen to be the main platform for IO virtualization in KVM |
| * The idea behind it is to have a common framework for hypervisors for IO virtualization | | * The idea behind it is to have a common framework for hypervisors for IO virtualization |
| * More information (although not uptodate) can be found [[Media:KvmForum2007$kvm_pv_drv.pdf|here]] | | * The specification can be found here: https://docs.oasis-open.org/virtio/virtio/v1.2/virtio-v1.2.html |
| * At the moment network/block/balloon devices are suported for kvm
| |
| * The host implementation is in userspace - qemu, so no driver is needed in the host.
| |
| | |
| == How to use Virtio ==
| |
| * Get kvm version >= 60
| |
| * Get Linux kernel with virtio drivers for the guest
| |
| ** Get Kernel >= 2.6.25 and activate (modules should also work, but take care of initramdisk)
| |
| *** CONFIG_VIRTIO_PCI=y (Virtualization -> PCI driver for virtio devices)
| |
| *** CONFIG_VIRTIO_BALLOON=y (Virtualization -> Virtio balloon driver)
| |
| *** CONFIG_VIRTIO_BLK=y (Device Drivers -> Block -> Virtio block driver)
| |
| *** CONFIG_VIRTIO_NET=y (Device Drivers -> Network device support -> Virtio network driver)
| |
| *** CONFIG_VIRTIO=y (automatically selected)
| |
| *** CONFIG_VIRTIO_RING=y (automatically selected)
| |
| *** you can safely disable SATA/SCSI and also all other nic drivers if you only use VIRTIO (disk/nic)
| |
| * As an alternative one can use a standard guest kernel for the guest > 2.6.18 and make use sync backward compatibility option
| |
| ** Backport and instructions can be found in [http://www.kernel.org/pub/scm/virt/kvm/kvm-guest-drivers-linux.git kvm-guest-drivers-linux.git]
| |
| * Use virtio-net-pci device for the network devices (or model=virtio for old -net..-net syntax) and if=virtio for disk
| |
| ** Example
| |
| <pre><nowiki>
| |
| x86_64-softmmu/qemu-system-x86_64 -boot c -drive file=/images/xpbase.qcow2,if=virtio -m 384 -netdev type=tap,script=/etc/kvm/qemu-ifup,id=net0 -device virtio-net-pci,netdev=net0
| |
| </nowiki></pre>
| |
| * -hd[ab] for disk won't work, use -drive
| |
| * Disk will show up as /dev/vd[a-z][1-9], if you migrate you need to change "root=" in Lilo/GRUB config
| |
| * At the moment the kernel modules are automatically loaded in the guest but the interface should be started manually (dhclient/ifconfig)
| |
| * Currently performance is much better when using a host kernel configured with CONFIG_HIGH_RES_TIMERS. Another option is use HPET/RTC and -clock= qemu option.
| |
| * Expected performance
| |
| ** Performance varies from host to host, kernel to kernel
| |
| ** On my laptop I measured 1.1Gbps rx throughput using 2.6.23, 850Mbps tx.
| |
| ** Ping latency is 300-500 usec
| |
| * Enjoy, more to come :)
| |
| | |
| == How to use get high performance with Virtio ==
| |
| * get the latest drop from [http://dpdk.org/download dpdk.org]
| |
| * add the [http://dpdk.org/browse/virtio-net-pmd/refs/ librte_pmd_virtio]
| |
| ** Example
| |
| <pre><nowiki>
| |
| testpmd -c 0xff -n 1 \
| |
| -d librte_pmd_virtio.so \
| |
| -- \
| |
| --disable-hw-vlan --disable-rss \
| |
| -i --rxq=1 --txq=1 --rxd=256 --txd=256
| |
| </nowiki></pre>
| |
|
| |
|
| __NOTOC__ | | __NOTOC__ |