.. BSD LICENSE
- Copyright(c) 2010-2015 Intel Corporation. All rights reserved.
+ Copyright(c) 2010-2016 Intel Corporation. All rights reserved.
All rights reserved.
Redistribution and use in source and binary forms, with or without
Vhost Sample Application
========================
-The vhost sample application demonstrates integration of the Data Plane Development Kit (DPDK)
-with the Linux* KVM hypervisor by implementing the vhost-net offload API.
-The sample application performs simple packet switching between virtual machines based on Media Access Control
-(MAC) address or Virtual Local Area Network (VLAN) tag.
-The splitting of Ethernet traffic from an external switch is performed in hardware by the Virtual Machine Device Queues
-(VMDQ) and Data Center Bridging (DCB) features of the Intel® 82599 10 Gigabit Ethernet Controller.
+The vhost sample application demonstrates integration of the Data Plane
+Development Kit (DPDK) with the Linux* KVM hypervisor by implementing the
+vhost-net offload API. The sample application performs simple packet
+switching between virtual machines based on Media Access Control (MAC)
+address or Virtual Local Area Network (VLAN) tag. The splitting of Ethernet
+traffic from an external switch is performed in hardware by the Virtual
+Machine Device Queues (VMDQ) and Data Center Bridging (DCB) features of
+the Intel® 82599 10 Gigabit Ethernet Controller.
-Background
-----------
-
-Virtio networking (virtio-net) was developed as the Linux* KVM para-virtualized method for communicating network packets
-between host and guest.
-It was found that virtio-net performance was poor due to context switching and packet copying between host, guest, and QEMU.
-The following figure shows the system architecture for a virtio-based networking (virtio-net).
-
-.. _figure_qemu_virtio_net:
-
-.. figure:: img/qemu_virtio_net.*
-
- System Architecture for Virtio-based Networking (virtio-net).
-
-
-The Linux* Kernel vhost-net module was developed as an offload mechanism for virtio-net.
-The vhost-net module enables KVM (QEMU) to offload the servicing of virtio-net devices to the vhost-net kernel module,
-reducing the context switching and packet copies in the virtual dataplane.
-
-This is achieved by QEMU sharing the following information with the vhost-net module through the vhost-net API:
-
-* The layout of the guest memory space, to enable the vhost-net module to translate addresses.
-
-* The locations of virtual queues in QEMU virtual address space,
- to enable the vhost module to read/write directly to and from the virtqueues.
-
-* An event file descriptor (eventfd) configured in KVM to send interrupts to the virtio- net device driver in the guest.
- This enables the vhost-net module to notify (call) the guest.
-
-* An eventfd configured in KVM to be triggered on writes to the virtio-net device's
- Peripheral Component Interconnect (PCI) config space.
- This enables the vhost-net module to receive notifications (kicks) from the guest.
-
-The following figure shows the system architecture for virtio-net networking with vhost-net offload.
-
-.. _figure_virtio_linux_vhost:
-
-.. figure:: img/virtio_linux_vhost.*
-
- Virtio with Linux
-
-
-Sample Code Overview
---------------------
-
-The DPDK vhost-net sample code demonstrates KVM (QEMU) offloading the servicing of a Virtual Machine's (VM's)
-virtio-net devices to a DPDK-based application in place of the kernel's vhost-net module.
-
-The DPDK vhost-net sample code is based on vhost library. Vhost library is developed for user space Ethernet switch to
-easily integrate with vhost functionality.
-
-The vhost library implements the following features:
-
-* Management of virtio-net device creation/destruction events.
-
-* Mapping of the VM's physical memory into the DPDK vhost-net's address space.
-
-* Triggering/receiving notifications to/from VMs via eventfds.
-
-* A virtio-net back-end implementation providing a subset of virtio-net features.
-
-There are two vhost implementations in vhost library, vhost cuse and vhost user. In vhost cuse, a character device driver is implemented to
-receive and process vhost requests through ioctl messages. In vhost user, a socket server is created to received vhost requests through
-socket messages. Most of the messages share the same handler routine.
-
-.. note::
- **Any vhost cuse specific requirement in the following sections will be emphasized**.
-
-Two implementations are turned on and off statically through configure file. Only one implementation could be turned on. They don't co-exist in current implementation.
-
-The vhost sample code application is a simple packet switching application with the following feature:
-
-* Packet switching between virtio-net devices and the network interface card,
- including using VMDQs to reduce the switching that needs to be performed in software.
-
-The following figure shows the architecture of the Vhost sample application based on vhost-cuse.
-
-.. _figure_vhost_net_arch:
-
-.. figure:: img/vhost_net_arch.*
-
- Vhost-net Architectural Overview
-
-
-The following figure shows the flow of packets through the vhost-net sample application.
-
-.. _figure_vhost_net_sample_app:
-
-.. figure:: img/vhost_net_sample_app.*
-
- Packet Flow Through the vhost-net Sample Application
-
-
-Supported Distributions
------------------------
-
-The example in this section have been validated with the following distributions:
-
-* Fedora* 18
-
-* Fedora* 19
-
-* Fedora* 20
-
-.. _vhost_app_prerequisites:
-
-Prerequisites
+Testing steps
-------------
-This section lists prerequisite packages that must be installed.
-
-Installing Packages on the Host(vhost cuse required)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-The vhost cuse code uses the following packages; fuse, fuse-devel, and kernel-modules-extra.
-The vhost user code don't rely on those modules as eventfds are already installed into vhost process through
-Unix domain socket.
-
-#. Install Fuse Development Libraries and headers:
-
- .. code-block:: console
-
- yum -y install fuse fuse-devel
-
-#. Install the Cuse Kernel Module:
-
- .. code-block:: console
-
- yum -y install kernel-modules-extra
-
-QEMU simulator
-~~~~~~~~~~~~~~
-
-For vhost user, qemu 2.2 is required.
-
-Setting up the Execution Environment
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-The vhost sample code requires that QEMU allocates a VM's memory on the hugetlbfs file system.
-As the vhost sample code requires hugepages,
-the best practice is to partition the system into separate hugepage mount points for the VMs and the vhost sample code.
-
-.. note::
-
- This is best-practice only and is not mandatory.
- For systems that only support 2 MB page sizes,
- both QEMU and vhost sample code can use the same hugetlbfs mount point without issue.
-
-**QEMU**
-
-VMs with gigabytes of memory can benefit from having QEMU allocate their memory from 1 GB huge pages.
-1 GB huge pages must be allocated at boot time by passing kernel parameters through the grub boot loader.
-
-#. Calculate the maximum memory usage of all VMs to be run on the system.
- Then, round this value up to the nearest Gigabyte the execution environment will require.
-
-#. Edit the /etc/default/grub file, and add the following to the GRUB_CMDLINE_LINUX entry:
-
- .. code-block:: console
-
- GRUB_CMDLINE_LINUX="... hugepagesz=1G hugepages=<Number of hugepages required> default_hugepagesz=1G"
-
-#. Update the grub boot loader:
-
- .. code-block:: console
-
- grub2-mkconfig -o /boot/grub2/grub.cfg
-
-#. Reboot the system.
-
-#. The hugetlbfs mount point (/dev/hugepages) should now default to allocating gigabyte pages.
-
-.. note::
-
- Making the above modification will change the system default hugepage size to 1 GB for all applications.
-
-**Vhost Sample Code**
-
-In this section, we create a second hugetlbs mount point to allocate hugepages for the DPDK vhost sample code.
-
-#. Allocate sufficient 2 MB pages for the DPDK vhost sample code:
-
- .. code-block:: console
-
- echo 256 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
-
-#. Mount hugetlbs at a separate mount point for 2 MB pages:
-
- .. code-block:: console
-
- mount -t hugetlbfs nodev /mnt/huge -o pagesize=2M
-
-The above steps can be automated by doing the following:
-
-#. Edit /etc/fstab to add an entry to automatically mount the second hugetlbfs mount point:
-
- ::
-
- hugetlbfs <tab> /mnt/huge <tab> hugetlbfs defaults,pagesize=1G 0 0
-
-#. Edit the /etc/default/grub file, and add the following to the GRUB_CMDLINE_LINUX entry:
-
- ::
-
- GRUB_CMDLINE_LINUX="... hugepagesz=2M hugepages=256 ... default_hugepagesz=1G"
-
-#. Update the grub bootloader:
-
- .. code-block:: console
-
- grub2-mkconfig -o /boot/grub2/grub.cfg
-
-#. Reboot the system.
-
-.. note::
-
- Ensure that the default hugepage size after this setup is 1 GB.
-
-Setting up the Guest Execution Environment
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-It is recommended for testing purposes that the DPDK testpmd sample application is used in the guest to forward packets,
-the reasons for this are discussed in `Running the Virtual Machine (QEMU)`_.
-
-The testpmd application forwards packets between pairs of Ethernet devices,
-it requires an even number of Ethernet devices (virtio or otherwise) to execute.
-It is therefore recommended to create multiples of two virtio-net devices for each Virtual Machine either through libvirt or
-at the command line as follows.
-
-.. note::
-
- Observe that in the example, "-device" and "-netdev" are repeated for two virtio-net devices.
-
-For vhost cuse:
-
-.. code-block:: console
-
- qemu-system-x86_64 ... \
- -netdev tap,id=hostnet1,vhost=on,vhostfd=<open fd> \
- -device virtio-net-pci, netdev=hostnet1,id=net1 \
- -netdev tap,id=hostnet2,vhost=on,vhostfd=<open fd> \
- -device virtio-net-pci, netdev=hostnet2,id=net1
-
-For vhost user:
-
-.. code-block:: console
-
- qemu-system-x86_64 ... \
- -chardev socket,id=char1,path=<sock_path> \
- -netdev type=vhost-user,id=hostnet1,chardev=char1 \
- -device virtio-net-pci,netdev=hostnet1,id=net1 \
- -chardev socket,id=char2,path=<sock_path> \
- -netdev type=vhost-user,id=hostnet2,chardev=char2 \
- -device virtio-net-pci,netdev=hostnet2,id=net2
-
-sock_path is the path for the socket file created by vhost.
-
-Compiling the Sample Code
--------------------------
-#. Compile vhost lib:
-
- To enable vhost, turn on vhost library in the configure file config/common_linuxapp.
-
- .. code-block:: console
-
- CONFIG_RTE_LIBRTE_VHOST=n
-
- vhost user is turned on by default in the configure file config/common_linuxapp.
- To enable vhost cuse, disable vhost user.
-
- .. code-block:: console
-
- CONFIG_RTE_LIBRTE_VHOST_USER=y
-
- After vhost is enabled and the implementation is selected, build the vhost library.
-
-#. Go to the examples directory:
-
- .. code-block:: console
-
- export RTE_SDK=/path/to/rte_sdk
- cd ${RTE_SDK}/examples/vhost
-
-#. Set the target (a default target is used if not specified). For example:
-
- .. code-block:: console
-
- export RTE_TARGET=x86_64-native-linuxapp-gcc
-
- See the DPDK Getting Started Guide for possible RTE_TARGET values.
-
-#. Build the application:
-
- .. code-block:: console
-
- cd ${RTE_SDK}
- make config ${RTE_TARGET}
- make install ${RTE_TARGET}
- cd ${RTE_SDK}/examples/vhost
- make
-
-#. Go to the eventfd_link directory(vhost cuse required):
-
- .. code-block:: console
-
- cd ${RTE_SDK}/lib/librte_vhost/eventfd_link
-
-#. Build the eventfd_link kernel module(vhost cuse required):
-
- .. code-block:: console
-
- make
-
-Running the Sample Code
------------------------
-
-#. Install the cuse kernel module(vhost cuse required):
-
- .. code-block:: console
-
- modprobe cuse
-
-#. Go to the eventfd_link directory(vhost cuse required):
-
- .. code-block:: console
+This section shows the steps how to test a typical PVP case with this
+vhost-switch sample, whereas packets are received from the physical NIC
+port first and enqueued to the VM's Rx queue. Through the guest testpmd's
+default forwarding mode (io forward), those packets will be put into
+the Tx queue. The vhost-switch example, in turn, gets the packets and
+puts back to the same physical NIC port.
- export RTE_SDK=/path/to/rte_sdk
- cd ${RTE_SDK}/lib/librte_vhost/eventfd_link
+Build
+~~~~~
-#. Install the eventfd_link module(vhost cuse required):
+Follow the *Getting Started Guide for Linux* on generic info about
+environment setup and building DPDK from source.
- .. code-block:: console
-
- insmod ./eventfd_link.ko
-
-#. Go to the examples directory:
-
- .. code-block:: console
-
- export RTE_SDK=/path/to/rte_sdk
- cd ${RTE_SDK}/examples/vhost/build/app
-
-#. Run the vhost-switch sample code:
-
- vhost cuse:
-
- .. code-block:: console
-
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- -p 0x1 --dev-basename usvhost
-
- vhost user: a socket file named usvhost will be created under current directory. Use its path as the socket path in guest's qemu commandline.
-
- .. code-block:: console
-
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- -p 0x1 --dev-basename usvhost
-
-.. note::
-
- Please note the huge-dir parameter instructs the DPDK to allocate its memory from the 2 MB page hugetlbfs.
-
-.. note::
-
- The number used with the --socket-mem parameter may need to be more than 1024.
- The number required depends on the number of mbufs allocated by vhost-switch.
-
-.. _vhost_app_parameters:
-
-Parameters
-~~~~~~~~~~
-
-**Basename.**
-vhost cuse uses a Linux* character device to communicate with QEMU.
-The basename is used to generate the character devices name.
-
- /dev/<basename>
-
-For compatibility with the QEMU wrapper script, a base name of "usvhost" should be used:
-
-.. code-block:: console
-
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- -p 0x1 --dev-basename usvhost
-
-**vm2vm.**
-The vm2vm parameter disable/set mode of packet switching between guests in the host.
-Value of "0" means disabling vm2vm implies that on virtual machine packet transmission will always go to the Ethernet port;
-Value of "1" means software mode packet forwarding between guests, it needs packets copy in vHOST,
-so valid only in one-copy implementation, and invalid for zero copy implementation;
-value of "2" means hardware mode packet forwarding between guests, it allows packets go to the Ethernet port,
-hardware L2 switch will determine which guest the packet should forward to or need send to external,
-which bases on the packet destination MAC address and VLAN tag.
-
-.. code-block:: console
-
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- --vm2vm [0,1,2]
-
-**Mergeable Buffers.**
-The mergeable buffers parameter controls how virtio-net descriptors are used for virtio-net headers.
-In a disabled state, one virtio-net header is used per packet buffer;
-in an enabled state one virtio-net header is used for multiple packets.
-The default value is 0 or disabled since recent kernels virtio-net drivers show performance degradation with this feature is enabled.
-
-.. code-block:: console
-
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- --mergeable [0,1]
-
-**Stats.**
-The stats parameter controls the printing of virtio-net device statistics.
-The parameter specifies an interval second to print statistics, with an interval of 0 seconds disabling statistics.
-
-.. code-block:: console
-
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- --stats [0,n]
-
-**RX Retry.**
-The rx-retry option enables/disables enqueue retries when the guests RX queue is full.
-This feature resolves a packet loss that is observed at high data-rates,
-by allowing it to delay and retry in the receive path.
-This option is enabled by default.
-
-.. code-block:: console
-
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- --rx-retry [0,1]
-
-**RX Retry Number.**
-The rx-retry-num option specifies the number of retries on an RX burst,
-it takes effect only when rx retry is enabled.
-The default value is 4.
+In this example, you need build DPDK both on the host and inside guest.
+Also, you need build this example.
.. code-block:: console
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- --rx-retry 1 --rx-retry-num 5
+ export RTE_SDK=/path/to/dpdk_source
+ export RTE_TARGET=x86_64-native-linuxapp-gcc
-**RX Retry Delay Time.**
-The rx-retry-delay option specifies the timeout (in micro seconds) between retries on an RX burst,
-it takes effect only when rx retry is enabled.
-The default value is 15.
+ cd ${RTE_SDK}/examples/vhost
+ make
-.. code-block:: console
-
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- --rx-retry 1 --rx-retry-delay 20
-
-**Zero copy.**
-Zero copy mode is removed, due to it has not been working for a while. And
-due to the large and complex code, it's better to redesign it than fixing
-it to make it work again. Hence, zero copy may be added back later.
-**VLAN strip.**
-The VLAN strip option enable/disable the VLAN strip on host, if disabled, the guest will receive the packets with VLAN tag.
-It is enabled by default.
+Start the vswitch example
+~~~~~~~~~~~~~~~~~~~~~~~~~
.. code-block:: console
- ./vhost-switch -c f -n 4 --socket-mem 1024 --huge-dir /mnt/huge \
- -- --vlan-strip [0, 1]
-
-.. _vhost_app_running:
-
-Running the Virtual Machine (QEMU)
-----------------------------------
-
-QEMU must be executed with specific parameters to:
-
-* Ensure the guest is configured to use virtio-net network adapters.
-
- .. code-block:: console
-
- qemu-system-x86_64 ... -device virtio-net-pci,netdev=hostnet1, \
- id=net1 ...
-
-* Ensure the guest's virtio-net network adapter is configured with offloads disabled.
-
- .. code-block:: console
-
- qemu-system-x86_64 ... -device virtio-net-pci,netdev=hostnet1, \
- id=net1, csum=off,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off
-
-* Redirect QEMU to communicate with the DPDK vhost-net sample code in place of the vhost-net kernel module(vhost cuse).
-
- .. code-block:: console
-
- qemu-system-x86_64 ... -netdev tap,id=hostnet1,vhost=on, \
- vhostfd=<open fd> ...
-
-* Enable the vhost-net sample code to map the VM's memory into its own process address space.
-
- .. code-block:: console
-
- qemu-system-x86_64 ... -mem-prealloc -mem-path /dev/hugepages ...
-
-.. note::
-
- The QEMU wrapper (qemu-wrap.py) is a Python script designed to automate the QEMU configuration described above.
- It also facilitates integration with libvirt, although the script may also be used standalone without libvirt.
-
-Redirecting QEMU to vhost-net Sample Code(vhost cuse)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-To redirect QEMU to the vhost-net sample code implementation of the vhost-net API,
-an open file descriptor must be passed to QEMU running as a child process.
-
-.. code-block:: python
-
- #!/usr/bin/python
- fd = os.open("/dev/usvhost-1", os.O_RDWR)
- subprocess.call
- ("qemu-system-x86_64 ... -netdev tap,id=vhostnet0,vhost=on,vhostfd="
- + fd +"...", shell=True)
-
-.. note::
+ ./vhost-switch -c f -n 4 --socket-mem 1024 \
+ -- --socket-file /tmp/sock0 --client \
+ ...
- This process is automated in the `QEMU Wrapper Script`_.
+Check the `Parameters`_ section for the explanations on what do those
+parameters mean.
-Mapping the Virtual Machine's Memory
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.. _vhost_app_run_vm:
-For the DPDK vhost-net sample code to be run correctly, QEMU must allocate the VM's memory on hugetlbfs.
-This is done by specifying mem-prealloc and mem-path when executing QEMU.
-The vhost-net sample code accesses the virtio-net device's virtual rings and packet buffers
-by finding and mapping the VM's physical memory on hugetlbfs.
-In this case, the path passed to the guest should be that of the 1 GB page hugetlbfs:
+Start the VM
+~~~~~~~~~~~~
.. code-block:: console
- qemu-system-x86_64 ... -mem-prealloc -mem-path /dev/hugepages ...
+ qemu-system-x86_64 -machine accel=kvm -cpu host \
+ -m $mem -object memory-backend-file,id=mem,size=$mem,mem-path=/dev/hugepages,share=on \
+ -mem-prealloc -numa node,memdev=mem \
+ \
+ -chardev socket,id=char1,path=/tmp/sock0,server \
+ -netdev type=vhost-user,id=hostnet1,chardev=char1 \
+ -device virtio-net-pci,netdev=hostnet1,id=net1,mac=52:54:00:00:00:14 \
+ ...
.. note::
+ For basic vhost-user support, QEMU 2.2 (or above) is required. For
+ some specific features, a higher version might be need. Such as
+ QEMU 2.7 (or above) for the reconnect feature.
- This process is automated in the `QEMU Wrapper Script`_.
- The following two sections only applies to vhost cuse.
- For vhost-user, please make corresponding changes to qemu-wrapper script and guest XML file.
+.. _vhost_app_run_dpdk_inside_guest:
-QEMU Wrapper Script
-~~~~~~~~~~~~~~~~~~~
+Run testpmd inside guest
+~~~~~~~~~~~~~~~~~~~~~~~~
-The QEMU wrapper script automatically detects and calls QEMU with the necessary parameters required
-to integrate with the vhost sample code.
-It performs the following actions:
-
-* Automatically detects the location of the hugetlbfs and inserts this into the command line parameters.
-
-* Automatically open file descriptors for each virtio-net device and inserts this into the command line parameters.
-
-* Disables offloads on each virtio-net device.
-
-* Calls Qemu passing both the command line parameters passed to the script itself and those it has auto-detected.
-
-The QEMU wrapper script will automatically configure calls to QEMU:
+Make sure you have DPDK built inside the guest. Also make sure the
+corresponding virtio-net PCI device is bond to a uio driver, which
+could be done by:
.. code-block:: console
- qemu-wrap.py -machine pc-i440fx-1.4,accel=kvm,usb=off \
- -cpu SandyBridge -smp 4,sockets=4,cores=1,threads=1 \
- -netdev tap,id=hostnet1,vhost=on \
- -device virtio-net-pci,netdev=hostnet1,id=net1 \
- -hda <disk img> -m 4096
+ modprobe uio_pci_generic
+ $RTE_SDK/tools/dpdk-devbind.py -b=uio_pci_generic 0000:00:04.0
-which will become the following call to QEMU:
+Then start testpmd for packet forwarding testing.
.. code-block:: console
- qemu-system-x86_64 -machine pc-i440fx-1.4,accel=kvm,usb=off \
- -cpu SandyBridge -smp 4,sockets=4,cores=1,threads=1 \
- -netdev tap,id=hostnet1,vhost=on,vhostfd=<open fd> \
- -device virtio-net-pci,netdev=hostnet1,id=net1, \
- csum=off,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off \
- -hda <disk img> -m 4096 -mem-path /dev/hugepages -mem-prealloc
-
-Libvirt Integration
-~~~~~~~~~~~~~~~~~~~
-
-The QEMU wrapper script (qemu-wrap.py) "wraps" libvirt calls to QEMU,
-such that QEMU is called with the correct parameters described above.
-To call the QEMU wrapper automatically from libvirt, the following configuration changes must be made:
-
-* Place the QEMU wrapper script in libvirt's binary search PATH ($PATH).
- A good location is in the directory that contains the QEMU binary.
-
-* Ensure that the script has the same owner/group and file permissions as the QEMU binary.
+ ./x86_64-native-gcc/app/testpmd -c 0x3 -- -i
+ > start tx_first
-* Update the VM xml file using virsh edit <vm name>:
+Inject packets
+--------------
- * Set the VM to use the launch script
+While a virtio-net is connected to vhost-switch, a VLAN tag starts with
+1000 is assigned to it. So make sure configure your packet generator
+with the right MAC and VLAN tag, you should be able to see following
+log from the vhost-switch console. It means you get it work::
- * Set the emulator path contained in the #<emulator><emulator/> tags For example,
- replace <emulator>/usr/bin/qemu-kvm<emulator/> with <emulator>/usr/bin/qemu-wrap.py<emulator/>
+ VHOST_DATA: (0) mac 52:54:00:00:00:14 and vlan 1000 registered
- * Set the VM's virtio-net device's to use vhost-net offload:
- .. code-block:: xml
-
- <interface type="network">
- <model type="virtio"/>
- <driver name="vhost"/>
- <interface/>
-
- * Enable libvirt to access the DPDK Vhost sample code's character device file by adding it
- to controllers cgroup for libvirtd using the following steps:
-
- .. code-block:: xml
-
- cgroup_controllers = [ ... "devices", ... ] clear_emulator_capabilities = 0
- user = "root" group = "root"
- cgroup_device_acl = [
- "/dev/null", "/dev/full", "/dev/zero",
- "/dev/random", "/dev/urandom",
- "/dev/ptmx", "/dev/kvm", "/dev/kqemu",
- "/dev/rtc", "/dev/hpet", "/dev/net/tun",
- "/dev/<devbase-name>-<index>",
- ]
-
-* Disable SELinux or set to permissive mode.
+.. _vhost_app_parameters:
+Parameters
+----------
-* Mount cgroup device controller:
+**--socket-file path**
+Specifies the vhost-user socket file path.
- .. code-block:: console
+**--client**
+DPDK vhost-user will act as the client mode when such option is given.
+In the client mode, QEMU will create the socket file. Otherwise, DPDK
+will create it. Put simply, it's the server to create the socket file.
- mkdir /dev/cgroup
- mount -t cgroup none /dev/cgroup -o devices
-* Restart the libvirtd system process
+**--vm2vm mode**
+The vm2vm parameter sets the mode of packet switching between guests in
+the host.
- For example, on Fedora* "systemctl restart libvirtd.service"
+- 0 disables vm2vm, impling that VM's packets will always go to the NIC port.
+- 1 means a normal mac lookup packet routing.
+- 2 means hardware mode packet forwarding between guests, it allows packets
+ go to the NIC port, hardware L2 switch will determine which guest the
+ packet should forward to or need send to external, which bases on the
+ packet destination MAC address and VLAN tag.
-* Edit the configuration parameters section of the script:
+**--mergeable 0|1**
+Set 0/1 to disable/enable the mergeable Rx feature. It's disabled by default.
- * Configure the "emul_path" variable to point to the QEMU emulator.
+**--stats interval**
+The stats parameter controls the printing of virtio-net device statistics.
+The parameter specifies an interval (in unit of seconds) to print statistics,
+with an interval of 0 seconds disabling statistics.
- .. code-block:: xml
+**--rx-retry 0|1**
+The rx-retry option enables/disables enqueue retries when the guests Rx queue
+is full. This feature resolves a packet loss that is observed at high data
+rates, by allowing it to delay and retry in the receive path. This option is
+enabled by default.
- emul_path = "/usr/local/bin/qemu-system-x86_64"
+**--rx-retry-num num**
+The rx-retry-num option specifies the number of retries on an Rx burst, it
+takes effect only when rx retry is enabled. The default value is 4.
- * Configure the "us_vhost_path" variable to point to the DPDK vhost-net sample code's character devices name.
- DPDK vhost-net sample code's character device will be in the format "/dev/<basename>".
+**--rx-retry-delay msec**
+The rx-retry-delay option specifies the timeout (in micro seconds) between
+retries on an RX burst, it takes effect only when rx retry is enabled. The
+default value is 15.
- .. code-block:: xml
+**--dequeue-zero-copy**
+Dequeue zero copy will be enabled when this option is given.
- us_vhost_path = "/dev/usvhost"
+**--vlan-strip 0|1**
+VLAN strip option is removed, because different NICs have different behaviors
+when disabling VLAN strip. Such feature, which heavily depends on hardware,
+should be removed from this example to reduce confusion. Now, VLAN strip is
+enabled and cannot be disabled.
Common Issues
-~~~~~~~~~~~~~
-
-* QEMU failing to allocate memory on hugetlbfs, with an error like the following::
-
- file_ram_alloc: can't mmap RAM pages: Cannot allocate memory
-
- When running QEMU the above error indicates that it has failed to allocate memory for the Virtual Machine on
- the hugetlbfs. This is typically due to insufficient hugepages being free to support the allocation request.
- The number of free hugepages can be checked as follows:
-
- .. code-block:: console
-
- cat /sys/kernel/mm/hugepages/hugepages-<pagesize>/nr_hugepages
-
- The command above indicates how many hugepages are free to support QEMU's allocation request.
-
-* User space VHOST when the guest has 2MB sized huge pages:
-
- The guest may have 2MB or 1GB sized huge pages. The user space VHOST should work properly in both cases.
-
-* User space VHOST will not work with QEMU without the ``-mem-prealloc`` option:
-
- The current implementation works properly only when the guest memory is pre-allocated, so it is required to
- use a QEMU version (e.g. 1.6) which supports ``-mem-prealloc``. The ``-mem-prealloc`` option must be
- specified explicitly in the QEMU command line.
-
-* User space VHOST will not work with a QEMU version without shared memory mapping:
-
- As shared memory mapping is mandatory for user space VHOST to work properly with the guest, user space VHOST
- needs access to the shared memory from the guest to receive and transmit packets. It is important to make sure
- the QEMU version supports shared memory mapping.
-
-* In an Ubuntu environment, QEMU fails to start a new guest normally with user space VHOST due to not being able
- to allocate huge pages for the new guest:
-
- The solution for this issue is to add ``-boot c`` into the QEMU command line to make sure the huge pages are
- allocated properly and then the guest should start normally.
-
- Use ``cat /proc/meminfo`` to check if there is any changes in the value of ``HugePages_Total`` and ``HugePages_Free``
- after the guest startup.
-
-* Log message: ``eventfd_link: module verification failed: signature and/or required key missing - tainting kernel``:
-
- This log message may be ignored. The message occurs due to the kernel module ``eventfd_link``, which is not a standard
- Linux module but which is necessary for the user space VHOST current implementation (CUSE-based) to communicate with
- the guest.
-
-.. _vhost_app_running_dpdk:
-
-Running DPDK in the Virtual Machine
------------------------------------
-
-For the DPDK vhost-net sample code to switch packets into the VM,
-the sample code must first learn the MAC address of the VM's virtio-net device.
-The sample code detects the address from packets being transmitted from the VM, similar to a learning switch.
-
-This behavior requires no special action or configuration with the Linux* virtio-net driver in the VM
-as the Linux* Kernel will automatically transmit packets during device initialization.
-However, DPDK-based applications must be modified to automatically transmit packets during initialization
-to facilitate the DPDK vhost- net sample code's MAC learning.
-
-The DPDK testpmd application can be configured to automatically transmit packets during initialization
-and to act as an L2 forwarding switch.
-
-Testpmd MAC Forwarding
-~~~~~~~~~~~~~~~~~~~~~~
-
-At high packet rates, a minor packet loss may be observed.
-To resolve this issue, a "wait and retry" mode is implemented in the testpmd and vhost sample code.
-In the "wait and retry" mode if the virtqueue is found to be full, then testpmd waits for a period of time before retrying to enqueue packets.
-
-The "wait and retry" algorithm is implemented in DPDK testpmd as a forwarding method call "mac_retry".
-The following sequence diagram describes the algorithm in detail.
-
-.. _figure_tx_dpdk_testpmd:
-
-.. figure:: img/tx_dpdk_testpmd.*
-
- Packet Flow on TX in DPDK-testpmd
-
-
-Running Testpmd
-~~~~~~~~~~~~~~~
-
-The testpmd application is automatically built when DPDK is installed.
-Run the testpmd application as follows:
-
-.. code-block:: console
-
- cd ${RTE_SDK}/x86_64-native-linuxapp-gcc/app
- ./testpmd -c 0x3 -n 4 --socket-mem 512 \
- -- --burst=64 --i --disable-hw-vlan-filter
-
-The destination MAC address for packets transmitted on each port can be set at the command line:
-
-.. code-block:: console
-
- ./testpmd -c 0x3 -n 4 --socket-mem 512 \
- -- --burst=64 --i --disable-hw-vlan-filter \
- --eth-peer=0,aa:bb:cc:dd:ee:ff --eth-peer=1,ff:ee:dd:cc:bb:aa
-
-* Packets received on port 1 will be forwarded on port 0 to MAC address
-
- aa:bb:cc:dd:ee:ff
-
-* Packets received on port 0 will be forwarded on port 1 to MAC address
-
- ff:ee:dd:cc:bb:aa
-
-The testpmd application can then be configured to act as an L2 forwarding application:
-
-.. code-block:: console
-
- testpmd> set fwd mac_retry
-
-The testpmd can then be configured to start processing packets,
-transmitting packets first so the DPDK vhost sample code on the host can learn the MAC address:
-
-.. code-block:: console
-
- testpmd> start tx_first
+-------------
-.. note::
+* QEMU fails to allocate memory on hugetlbfs, with an error like the
+ following::
- Please note "set fwd mac_retry" is used in place of "set fwd mac_fwd" to ensure the retry feature is activated.
+ file_ram_alloc: can't mmap RAM pages: Cannot allocate memory
-Passing Traffic to the Virtual Machine Device
----------------------------------------------
+ When running QEMU the above error indicates that it has failed to allocate
+ memory for the Virtual Machine on the hugetlbfs. This is typically due to
+ insufficient hugepages being free to support the allocation request. The
+ number of free hugepages can be checked as follows:
-For a virtio-net device to receive traffic,
-the traffic's Layer 2 header must include both the virtio-net device's MAC address and VLAN tag.
-The DPDK sample code behaves in a similar manner to a learning switch in that
-it learns the MAC address of the virtio-net devices from the first transmitted packet.
-On learning the MAC address,
-the DPDK vhost sample code prints a message with the MAC address and VLAN tag virtio-net device.
-For example:
+ .. code-block:: console
-.. code-block:: console
+ cat /sys/kernel/mm/hugepages/hugepages-<pagesize>/nr_hugepages
- DATA: (0) MAC_ADDRESS cc:bb:bb:bb:bb:bb and VLAN_TAG 1000 registered
+ The command above indicates how many hugepages are free to support QEMU's
+ allocation request.
-The above message indicates that device 0 has been registered with MAC address cc:bb:bb:bb:bb:bb and VLAN tag 1000.
-Any packets received on the NIC with these values is placed on the devices receive queue.
-When a virtio-net device transmits packets, the VLAN tag is added to the packet by the DPDK vhost sample code.
+* vhost-user will not work with QEMU without the ``-mem-prealloc`` option
-Running virtio_user with vhost-switch
--------------------------------------
+ The current implementation works properly only when the guest memory is
+ pre-allocated.
-We can also use virtio_user with vhost-switch now.
-Virtio_user is a virtual device that can be run in a application (container) parallelly with vhost in the same OS,
-aka, there is no need to start a VM. We just run it with a different --file-prefix to avoid startup failure.
+* vhost-user will not work with a QEMU version without shared memory mapping:
-.. code-block:: console
+ Make sure ``share=on`` QEMU option is given.
- cd ${RTE_SDK}/x86_64-native-linuxapp-gcc/app
- ./testpmd -c 0x3 -n 4 --socket-mem 1024 --no-pci --file-prefix=virtio_user-testpmd \
- --vdev=virtio_user0,mac=00:01:02:03:04:05,path=$path_vhost \
- -- -i --txqflags=0xf01 --disable-hw-vlan
+* Failed to build DPDK in VM
-There is no difference on the vhost side.
-Pleae note that there are some limitations (see release note for more information) in the usage of virtio_user.
+ Make sure "-cpu host" QEMU option is given.
Code Review / deb_dpdk.git / blobdiff