1 Using Open vSwitch with DPDK
2 ============================
4 Open vSwitch can use Intel(R) DPDK lib to operate entirely in
5 userspace. This file explains how to install and use Open vSwitch in
8 The DPDK support of Open vSwitch is considered experimental.
9 It has not been thoroughly tested.
11 This version of Open vSwitch should be built manually with `configure`
14 OVS needs a system with 1GB hugepages support.
16 Building and Installing:
17 ------------------------
19 Required DPDK 1.8.0, `fuse`, `fuse-devel` (`libfuse-dev` on Debian/Ubuntu)
21 1. Configure build & install DPDK:
25 export DPDK_DIR=/usr/src/dpdk-1.8.0
29 2. Update `config/common_linuxapp` so that DPDK generate single lib file.
30 (modification also required for IVSHMEM build)
32 `CONFIG_RTE_BUILD_COMBINE_LIBS=y`
34 Update `config/common_linuxapp` so that DPDK is built with vhost
37 `CONFIG_RTE_LIBRTE_VHOST=y`
39 Then run `make install` to build and install the library.
40 For default install without IVSHMEM:
42 `make install T=x86_64-native-linuxapp-gcc`
44 To include IVSHMEM (shared memory):
46 `make install T=x86_64-ivshmem-linuxapp-gcc`
48 For further details refer to http://dpdk.org/
50 2. Configure & build the Linux kernel:
52 Refer to intel-dpdk-getting-started-guide.pdf for understanding
53 DPDK kernel requirement.
55 3. Configure & build OVS:
59 `export DPDK_BUILD=$DPDK_DIR/x86_64-native-linuxapp-gcc/`
63 `export DPDK_BUILD=$DPDK_DIR/x86_64-ivshmem-linuxapp-gcc/`
66 cd $(OVS_DIR)/openvswitch
68 ./configure --with-dpdk=$DPDK_BUILD
72 To have better performance one can enable aggressive compiler optimizations and
73 use the special instructions(popcnt, crc32) that may not be available on all
74 machines. Instead of typing `make`, type:
76 `make CFLAGS='-O3 -march=native'`
78 Refer to [INSTALL.userspace.md] for general requirements of building userspace OVS.
80 Using the DPDK with ovs-vswitchd:
81 ---------------------------------
84 Add the following options to the kernel bootline:
86 `default_hugepagesz=1GB hugepagesz=1G hugepages=1`
88 2. Setup DPDK devices:
90 DPDK devices can be setup using either the VFIO (for DPDK 1.7+) or UIO
91 modules. UIO requires inserting an out of tree driver igb_uio.ko that is
92 available in DPDK. Setup for both methods are described below.
95 1. insert uio.ko: `modprobe uio`
96 2. insert igb_uio.ko: `insmod $DPDK_BUILD/kmod/igb_uio.ko`
97 3. Bind network device to igb_uio:
98 `$DPDK_DIR/tools/dpdk_nic_bind.py --bind=igb_uio eth1`
102 VFIO needs to be supported in the kernel and the BIOS. More information
103 can be found in the [DPDK Linux GSG].
105 1. Insert vfio-pci.ko: `modprobe vfio-pci`
106 2. Set correct permissions on vfio device: `sudo /usr/bin/chmod a+x /dev/vfio`
107 and: `sudo /usr/bin/chmod 0666 /dev/vfio/*`
108 3. Bind network device to vfio-pci:
109 `$DPDK_DIR/tools/dpdk_nic_bind.py --bind=vfio-pci eth1`
111 3. Mount the hugetable filsystem
113 `mount -t hugetlbfs -o pagesize=1G none /dev/hugepages`
115 Ref to http://www.dpdk.org/doc/quick-start for verifying DPDK setup.
117 4. Follow the instructions in [INSTALL.md] to install only the
118 userspace daemons and utilities (via 'make install').
119 1. First time only db creation (or clearing):
122 mkdir -p /usr/local/etc/openvswitch
123 mkdir -p /usr/local/var/run/openvswitch
124 rm /usr/local/etc/openvswitch/conf.db
125 ovsdb-tool create /usr/local/etc/openvswitch/conf.db \
126 /usr/local/share/openvswitch/vswitch.ovsschema
129 2. Start ovsdb-server
132 ovsdb-server --remote=punix:/usr/local/var/run/openvswitch/db.sock \
133 --remote=db:Open_vSwitch,Open_vSwitch,manager_options \
134 --private-key=db:Open_vSwitch,SSL,private_key \
135 --certificate=Open_vSwitch,SSL,certificate \
136 --bootstrap-ca-cert=db:Open_vSwitch,SSL,ca_cert --pidfile --detach
139 3. First time after db creation, initialize:
142 ovs-vsctl --no-wait init
147 DPDK configuration arguments can be passed to vswitchd via `--dpdk`
148 argument. This needs to be first argument passed to vswitchd process.
149 dpdk arg -c is ignored by ovs-dpdk, but it is a required parameter
150 for dpdk initialization.
153 export DB_SOCK=/usr/local/var/run/openvswitch/db.sock
154 ovs-vswitchd --dpdk -c 0x1 -n 4 -- unix:$DB_SOCK --pidfile --detach
157 If allocated more than one GB hugepage (as for IVSHMEM), set amount and
158 use NUMA node 0 memory:
161 ovs-vswitchd --dpdk -c 0x1 -n 4 --socket-mem 1024,0 \
162 -- unix:$DB_SOCK --pidfile --detach
165 6. Add bridge & ports
167 To use ovs-vswitchd with DPDK, create a bridge with datapath_type
168 "netdev" in the configuration database. For example:
170 `ovs-vsctl add-br br0 -- set bridge br0 datapath_type=netdev`
172 Now you can add dpdk devices. OVS expect DPDK device name start with dpdk
173 and end with portid. vswitchd should print (in the log file) the number
174 of dpdk devices found.
177 ovs-vsctl add-port br0 dpdk0 -- set Interface dpdk0 type=dpdk
178 ovs-vsctl add-port br0 dpdk1 -- set Interface dpdk1 type=dpdk
181 Once first DPDK port is added to vswitchd, it creates a Polling thread and
182 polls dpdk device in continuous loop. Therefore CPU utilization
183 for that thread is always 100%.
187 Test flow script across NICs (assuming ovs in /usr/src/ovs):
192 # Move to command directory
193 cd /usr/src/ovs/utilities/
195 # Clear current flows
196 ./ovs-ofctl del-flows br0
198 # Add flows between port 1 (dpdk0) to port 2 (dpdk1)
199 ./ovs-ofctl add-flow br0 in_port=1,action=output:2
200 ./ovs-ofctl add-flow br0 in_port=2,action=output:1
203 8. Performance tuning
205 With pmd multi-threading support, OVS creates one pmd thread for each
206 numa node as default. The pmd thread handles the I/O of all DPDK
207 interfaces on the same numa node. The following two commands can be used
208 to configure the multi-threading behavior.
210 `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=<hex string>`
212 The command above asks for a CPU mask for setting the affinity of pmd
213 threads. A set bit in the mask means a pmd thread is created and pinned
214 to the corresponding CPU core. For more information, please refer to
215 `man ovs-vswitchd.conf.db`
217 `ovs-vsctl set Open_vSwitch . other_config:n-dpdk-rxqs=<integer>`
219 The command above sets the number of rx queues of each DPDK interface. The
220 rx queues are assigned to pmd threads on the same numa node in round-robin
221 fashion. For more information, please refer to `man ovs-vswitchd.conf.db`
223 Ideally for maximum throughput, the pmd thread should not be scheduled out
224 which temporarily halts its execution. The following affinitization methods
227 Lets pick core 4,6,8,10 for pmd threads to run on. Also assume a dual 8 core
228 sandy bridge system with hyperthreading enabled where CPU1 has cores 0,...,7
229 and 16,...,23 & CPU2 cores 8,...,15 & 24,...,31. (A different cpu
230 configuration could have different core mask requirements).
232 To kernel bootline add core isolation list for cores and associated hype cores
233 (e.g. isolcpus=4,20,6,22,8,24,10,26,). Reboot system for isolation to take
234 effect, restart everything.
236 Configure pmd threads on core 4,6,8,10 using 'pmd-cpu-mask':
238 `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=00000550`
240 You should be able to check that pmd threads are pinned to the correct cores
244 top -p `pidof ovs-vswitchd` -H -d1
247 Note, the pmd threads on a numa node are only created if there is at least
248 one DPDK interface from the numa node that has been added to OVS.
250 Note, core 0 is always reserved from non-pmd threads and should never be set
256 Following the steps above to create a bridge, you can now add dpdk rings
257 as a port to the vswitch. OVS will expect the DPDK ring device name to
258 start with dpdkr and end with a portid.
260 `ovs-vsctl add-port br0 dpdkr0 -- set Interface dpdkr0 type=dpdkr`
262 DPDK rings client test application
264 Included in the test directory is a sample DPDK application for testing
265 the rings. This is from the base dpdk directory and modified to work
266 with the ring naming used within ovs.
268 location tests/ovs_client
273 cd /usr/src/ovs/tests/
274 ovsclient -c 1 -n 4 --proc-type=secondary -- -n "port id you gave dpdkr"
277 In the case of the dpdkr example above the "port id you gave dpdkr" is 0.
279 It is essential to have --proc-type=secondary
281 The application simply receives an mbuf on the receive queue of the
282 ethernet ring and then places that same mbuf on the transmit ring of
283 the ethernet ring. It is a trivial loopback application.
285 DPDK rings in VM (IVSHMEM shared memory communications)
286 -------------------------------------------------------
288 In addition to executing the client in the host, you can execute it within
289 a guest VM. To do so you will need a patched qemu. You can download the
290 patch and getting started guide at :
292 https://01.org/packet-processing/downloads
294 A general rule of thumb for better performance is that the client
295 application should not be assigned the same dpdk core mask "-c" as
301 vhost-cuse is only supported at present i.e. not using the standard QEMU
302 vhost-user interface. It is intended that vhost-user support will be added
303 in future releases when supported in DPDK and that vhost-cuse will eventually
304 be deprecated. See [DPDK Docs] for more info on vhost.
307 1. Insert the Cuse module:
311 2. Build and insert the `eventfd_link` module:
313 `cd $DPDK_DIR/lib/librte_vhost/eventfd_link/`
315 `insmod $DPDK_DIR/lib/librte_vhost/eventfd_link.ko`
317 Following the steps above to create a bridge, you can now add DPDK vhost
318 as a port to the vswitch.
320 `ovs-vsctl add-port br0 dpdkvhost0 -- set Interface dpdkvhost0 type=dpdkvhost`
322 Unlike DPDK ring ports, DPDK vhost ports can have arbitrary names:
324 `ovs-vsctl add-port br0 port123ABC -- set Interface port123ABC type=dpdkvhost`
326 However, please note that when attaching userspace devices to QEMU, the
327 name provided during the add-port operation must match the ifname parameter
328 on the QEMU command line.
331 DPDK vhost VM configuration:
332 ----------------------------
334 vhost ports use a Linux* character device to communicate with QEMU.
335 By default it is set to `/dev/vhost-net`. It is possible to reuse this
336 standard device for DPDK vhost, which makes setup a little simpler but it
337 is better practice to specify an alternative character device in order to
338 avoid any conflicts if kernel vhost is to be used in parallel.
340 1. This step is only needed if using an alternative character device.
342 The new character device filename must be specified on the vswitchd
345 `./vswitchd/ovs-vswitchd --dpdk --cuse_dev_name my-vhost-net -c 0x1 ...`
347 Note that the `--cuse_dev_name` argument and associated string must be the first
348 arguments after `--dpdk` and come before the EAL arguments. In the example
349 above, the character device to be used will be `/dev/my-vhost-net`.
351 2. This step is only needed if reusing the standard character device. It will
352 conflict with the kernel vhost character device so the user must first
355 `rm -rf /dev/vhost-net`
357 3a. Configure virtio-net adaptors:
358 The following parameters must be passed to the QEMU binary:
361 -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on
362 -device virtio-net-pci,netdev=net1,mac=<mac>
365 Repeat the above parameters for multiple devices.
367 The DPDK vhost library will negiotiate its own features, so they
368 need not be passed in as command line params. Note that as offloads are
369 disabled this is the equivalent of setting:
371 `csum=off,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off`
373 3b. If using an alternative character device. It must be also explicitly
374 passed to QEMU using the `vhostfd` argument:
377 -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on,
379 -device virtio-net-pci,netdev=net1,mac=<mac>
382 The open file descriptor must be passed to QEMU running as a child
383 process. This could be done with a simple python script.
387 fd = os.open("/dev/usvhost", os.O_RDWR)
388 subprocess.call("qemu-system-x86_64 .... -netdev tap,id=vhostnet0,\
389 vhost=on,vhostfd=" + fd +"...", shell=True)
391 Alternatively the the `qemu-wrap.py` script can be used to automate the
392 requirements specified above and can be used in conjunction with libvirt if
393 desired. See the "DPDK vhost VM configuration with QEMU wrapper" section
396 4. Configure huge pages:
397 QEMU must allocate the VM's memory on hugetlbfs. Vhost ports access a
398 virtio-net device's virtual rings and packet buffers mapping the VM's
399 physical memory on hugetlbfs. To enable vhost-ports to map the VM's
400 memory into their process address space, pass the following paramters
403 `-object memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages,
404 share=on -numa node,memdev=mem -mem-prealloc`
407 DPDK vhost VM configuration with QEMU wrapper:
408 ----------------------------------------------
410 The QEMU wrapper script automatically detects and calls QEMU with the
411 necessary parameters. It performs the following actions:
413 * Automatically detects the location of the hugetlbfs and inserts this
414 into the command line parameters.
415 * Automatically open file descriptors for each virtio-net device and
416 inserts this into the command line parameters.
417 * Calls QEMU passing both the command line parameters passed to the
418 script itself and those it has auto-detected.
420 Before use, you **must** edit the configuration parameters section of the
421 script to point to the correct emulator location and set additional
422 settings. Of these settings, `emul_path` and `us_vhost_path` **must** be
423 set. All other settings are optional.
425 To use directly from the command line simply pass the wrapper some of the
426 QEMU parameters: it will configure the rest. For example:
429 qemu-wrap.py -cpu host -boot c -hda <disk image> -m 4096 -smp 4
430 --enable-kvm -nographic -vnc none -net none -netdev tap,id=net1,
431 script=no,downscript=no,ifname=if1,vhost=on -device virtio-net-pci,
432 netdev=net1,mac=00:00:00:00:00:01
435 DPDK vhost VM configuration with libvirt:
436 -----------------------------------------
438 If you are using libvirt, you must enable libvirt to access the character
439 device by adding it to controllers cgroup for libvirtd using the following
442 1. In `/etc/libvirt/qemu.conf` add/edit the following lines:
445 1) clear_emulator_capabilities = 0
448 4) cgroup_device_acl = [
449 "/dev/null", "/dev/full", "/dev/zero",
450 "/dev/random", "/dev/urandom",
451 "/dev/ptmx", "/dev/kvm", "/dev/kqemu",
452 "/dev/rtc", "/dev/hpet", "/dev/net/tun",
453 "/dev/<my-vhost-device>",
457 <my-vhost-device> refers to "vhost-net" if using the `/dev/vhost-net`
458 device. If you have specificed a different name on the ovs-vswitchd
459 commandline using the "--cuse_dev_name" parameter, please specify that
462 2. Disable SELinux or set to permissive mode
464 3. Restart the libvirtd process
465 For example, on Fedora:
467 `systemctl restart libvirtd.service`
469 After successfully editing the configuration, you may launch your
470 vhost-enabled VM. The XML describing the VM can be configured like so
471 within the <qemu:commandline> section:
473 1. Set up shared hugepages:
476 <qemu:arg value='-object'/>
477 <qemu:arg value='memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages,share=on'/>
478 <qemu:arg value='-numa'/>
479 <qemu:arg value='node,memdev=mem'/>
480 <qemu:arg value='-mem-prealloc'/>
483 2. Set up your tap devices:
486 <qemu:arg value='-netdev'/>
487 <qemu:arg value='type=tap,id=net1,script=no,downscript=no,ifname=vhost0,vhost=on'/>
488 <qemu:arg value='-device'/>
489 <qemu:arg value='virtio-net-pci,netdev=net1,mac=00:00:00:00:00:01'/>
492 Repeat for as many devices as are desired, modifying the id, ifname
493 and mac as necessary.
495 Again, if you are using an alternative character device (other than
496 `/dev/vhost-net`), please specify the file descriptor like so:
498 `<qemu:arg value='type=tap,id=net3,script=no,downscript=no,ifname=vhost0,vhost=on,vhostfd=<open_fd>'/>`
500 Where <open_fd> refers to the open file descriptor of the character device.
501 Instructions of how to retrieve the file descriptor can be found in the
502 "DPDK vhost VM configuration" section.
503 Alternatively, the process is automated with the qemu-wrap.py script,
504 detailed in the next section.
506 Now you may launch your VM using virt-manager, or like so:
508 `virsh create my_vhost_vm.xml`
510 DPDK vhost VM configuration with libvirt and QEMU wrapper:
511 ----------------------------------------------------------
513 To use the qemu-wrapper script in conjuntion with libvirt, follow the
514 steps in the previous section before proceeding with the following steps:
516 1. Place `qemu-wrap.py` in libvirtd's binary search PATH ($PATH)
517 Ideally in the same directory that the QEMU binary is located.
519 2. Ensure that the script has the same owner/group and file permissions
522 3. Update the VM xml file using "virsh edit VM.xml"
524 1. Set the VM to use the launch script.
525 Set the emulator path contained in the `<emulator><emulator/>` tags.
526 For example, replace:
528 `<emulator>/usr/bin/qemu-kvm<emulator/>`
532 `<emulator>/usr/bin/qemu-wrap.py<emulator/>`
534 4. Edit the Configuration Parameters section of the script to point to
535 the correct emulator location and set any additional options. If you are
536 using a alternative character device name, please set "us_vhost_path" to the
537 location of that device. The script will automatically detect and insert
538 the correct "vhostfd" value in the QEMU command line arguements.
540 5. Use virt-manager to launch the VM
545 - Work with 1500 MTU, needs few changes in DPDK lib to fix this issue.
546 - Currently DPDK port does not make use any offload functionality.
547 - DPDK-vHost support works with 1G huge pages.
550 - The shared memory is currently restricted to the use of a 1GB
552 - All huge pages are shared amongst the host, clients, virtual
558 Please report problems to bugs@openvswitch.org.
560 [INSTALL.userspace.md]:INSTALL.userspace.md
561 [INSTALL.md]:INSTALL.md
562 [DPDK Linux GSG]: http://www.dpdk.org/doc/guides/linux_gsg/build_dpdk.html#binding-and-unbinding-network-ports-to-from-the-igb-uioor-vfio-modules
563 [DPDK Docs]: http://dpdk.org/doc