X-Git-Url: http://git.droids-corp.org/?a=blobdiff_plain;f=doc%2Fguides%2Fnics%2Fvirtio.rst;h=90751e934a1f5b5583e44240994fdabd9a80bd71;hb=8b9bd0efe0b6;hp=c6335d405d1bbc0c99e04b54f4d80102b393dec4;hpb=c34673bb005e0d219c8774fe97e43067ab1d56a7;p=dpdk.git diff --git a/doc/guides/nics/virtio.rst b/doc/guides/nics/virtio.rst index c6335d405d..90751e934a 100644 --- a/doc/guides/nics/virtio.rst +++ b/doc/guides/nics/virtio.rst @@ -34,6 +34,7 @@ Poll Mode Driver for Emulated Virtio NIC Virtio is a para-virtualization framework initiated by IBM, and supported by KVM hypervisor. In the Data Plane Development Kit (DPDK), we provide a virtio Poll Mode Driver (PMD) as a software solution, comparing to SRIOV hardware solution, + for fast guest VM to guest VM communication and guest VM to host communication. Vhost is a kernel acceleration module for virtio qemu backend. @@ -41,9 +42,6 @@ The DPDK extends kni to support vhost raw socket interface, which enables vhost to directly read/ write packets from/to a physical port. With this enhancement, virtio could achieve quite promising performance. -In future release, we will also make enhancement to vhost backend, -releasing peak performance of virtio PMD driver. - For basic qemu-KVM installation and other Intel EM poll mode driver in guest VM, please refer to Chapter "Driver for VM Emulated Devices". @@ -73,20 +71,28 @@ In this release, the virtio PMD driver provides the basic functionality of packe * It supports multicast packets and promiscuous mode. -* The descriptor number for the Rx/Tx queue is hard-coded to be 256 by qemu. +* The descriptor number for the Rx/Tx queue is hard-coded to be 256 by qemu 2.7 and below. If given a different descriptor number by the upper application, the virtio PMD generates a warning and fall back to the hard-coded value. + Rx queue size can be configureable and up to 1024 since qemu 2.8 and above. Rx queue size is 256 + by default. Tx queue size is still hard-coded to be 256. * Features of mac/vlan filter are supported, negotiation with vhost/backend are needed to support them. - When backend can't support vlan filter, virtio app on guest should disable vlan filter to make sure - the virtio port is configured correctly. E.g. specify '--disable-hw-vlan' in testpmd command line. + When backend can't support vlan filter, virtio app on guest should not enable vlan filter in order + to make sure the virtio port is configured correctly. E.g. do not specify '--enable-hw-vlan' in testpmd + command line. -* RTE_PKTMBUF_HEADROOM should be defined larger than sizeof(struct virtio_net_hdr), which is 10 bytes. +* "RTE_PKTMBUF_HEADROOM" should be defined + no less than "sizeof(struct virtio_net_hdr_mrg_rxbuf)", which is 12 bytes when mergeable or + "VIRTIO_F_VERSION_1" is set. + no less than "sizeof(struct virtio_net_hdr)", which is 10 bytes, when using non-mergeable. * Virtio does not support runtime configuration. * Virtio supports Link State interrupt. +* Virtio supports Rx interrupt (so far, only support 1:1 mapping for queue/interrupt). + * Virtio supports software vlan stripping and inserting. * Virtio supports using port IO to get PCI resource when uio/igb_uio module is not available. @@ -128,7 +134,7 @@ Host2VM communication example .. code-block:: console - examples/kni/build/app/kni -c 0xf -n 4 -- -p 0x1 -P --config="(0,1,3)" + examples/kni/build/app/kni -l 0-3 -n 4 -- -p 0x1 -P --config="(0,1,3)" This command generates one network device vEth0 for physical port. If specify more physical ports, the generated network device will be vEth1, vEth2, and so on. @@ -172,7 +178,7 @@ Host2VM communication example modprobe uio echo 512 > /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages modprobe uio_pci_generic - python tools/dpdk_nic_bind.py -b uio_pci_generic 00:03.0 + python usertools/dpdk-devbind.py -b uio_pci_generic 00:03.0 We use testpmd as the forwarding application in this example. @@ -273,4 +279,69 @@ The corresponding callbacks are: Example of using the vector version of the virtio poll mode driver in ``testpmd``:: - testpmd -c 0x7 -n 4 -- -i --txqflags=0xF01 --rxq=1 --txq=1 --nb-cores=1 + testpmd -l 0-2 -n 4 -- -i --txqflags=0xF01 --rxq=1 --txq=1 --nb-cores=1 + + +Interrupt mode +-------------- + +.. _virtio_interrupt_mode: + +There are three kinds of interrupts from a virtio device over PCI bus: config +interrupt, Rx interrupts, and Tx interrupts. Config interrupt is used for +notification of device configuration changes, especially link status (lsc). +Interrupt mode is translated into Rx interrupts in the context of DPDK. + +.. Note:: + + Virtio PMD already has support for receiving lsc from qemu when the link + status changes, especially when vhost user disconnects. However, it fails + to do that if the VM is created by qemu 2.6.2 or below, since the + capability to detect vhost user disconnection is introduced in qemu 2.7.0. + +Prerequisites for Rx interrupts +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +To support Rx interrupts, +#. Check if guest kernel supports VFIO-NOIOMMU: + + Linux started to support VFIO-NOIOMMU since 4.8.0. Make sure the guest + kernel is compiled with: + + .. code-block:: console + + CONFIG_VFIO_NOIOMMU=y + +#. Properly set msix vectors when starting VM: + + Enable multi-queue when starting VM, and specify msix vectors in qemu + cmdline. (N+1) is the minimum, and (2N+2) is mostly recommended. + + .. code-block:: console + + $(QEMU) ... -device virtio-net-pci,mq=on,vectors=2N+2 ... + +#. In VM, insert vfio module in NOIOMMU mode: + + .. code-block:: console + + modprobe vfio enable_unsafe_noiommu_mode=1 + modprobe vfio-pci + +#. In VM, bind the virtio device with vfio-pci: + + .. code-block:: console + + python usertools/dpdk-devbind.py -b vfio-pci 00:03.0 + +Example +~~~~~~~ + +Here we use l3fwd-power as an example to show how to get started. + + Example: + + .. code-block:: console + + $ l3fwd-power -l 0-1 -- -p 1 -P --config="(0,0,1)" \ + --no-numa --parse-ptype