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 ------------------------
20 Optional (if building with vhost-cuse): `fuse`, `fuse-devel` (`libfuse-dev`
23 1. Configure build & install DPDK:
27 export DPDK_DIR=/usr/src/dpdk-2.0
31 2. Update `config/common_linuxapp` so that DPDK generate single lib file.
32 (modification also required for IVSHMEM build)
34 `CONFIG_RTE_BUILD_COMBINE_LIBS=y`
36 Update `config/common_linuxapp` so that DPDK is built with vhost
39 `CONFIG_RTE_LIBRTE_VHOST=y`
41 Then run `make install` to build and install the library.
42 For default install without IVSHMEM:
44 `make install T=x86_64-native-linuxapp-gcc`
46 To include IVSHMEM (shared memory):
48 `make install T=x86_64-ivshmem-linuxapp-gcc`
50 For further details refer to http://dpdk.org/
52 2. Configure & build the Linux kernel:
54 Refer to intel-dpdk-getting-started-guide.pdf for understanding
55 DPDK kernel requirement.
57 3. Configure & build OVS:
61 `export DPDK_BUILD=$DPDK_DIR/x86_64-native-linuxapp-gcc/`
65 `export DPDK_BUILD=$DPDK_DIR/x86_64-ivshmem-linuxapp-gcc/`
68 cd $(OVS_DIR)/openvswitch
70 ./configure --with-dpdk=$DPDK_BUILD [CFLAGS="-g -O2 -Wno-cast-align"]
74 Note: 'clang' users may specify the '-Wno-cast-align' flag to suppress DPDK cast-align warnings.
76 To have better performance one can enable aggressive compiler optimizations and
77 use the special instructions(popcnt, crc32) that may not be available on all
78 machines. Instead of typing `make`, type:
80 `make CFLAGS='-O3 -march=native'`
82 Refer to [INSTALL.userspace.md] for general requirements of building userspace OVS.
84 Using the DPDK with ovs-vswitchd:
85 ---------------------------------
88 Add the following options to the kernel bootline:
90 `default_hugepagesz=1GB hugepagesz=1G hugepages=1`
92 2. Setup DPDK devices:
94 DPDK devices can be setup using either the VFIO (for DPDK 1.7+) or UIO
95 modules. UIO requires inserting an out of tree driver igb_uio.ko that is
96 available in DPDK. Setup for both methods are described below.
99 1. insert uio.ko: `modprobe uio`
100 2. insert igb_uio.ko: `insmod $DPDK_BUILD/kmod/igb_uio.ko`
101 3. Bind network device to igb_uio:
102 `$DPDK_DIR/tools/dpdk_nic_bind.py --bind=igb_uio eth1`
106 VFIO needs to be supported in the kernel and the BIOS. More information
107 can be found in the [DPDK Linux GSG].
109 1. Insert vfio-pci.ko: `modprobe vfio-pci`
110 2. Set correct permissions on vfio device: `sudo /usr/bin/chmod a+x /dev/vfio`
111 and: `sudo /usr/bin/chmod 0666 /dev/vfio/*`
112 3. Bind network device to vfio-pci:
113 `$DPDK_DIR/tools/dpdk_nic_bind.py --bind=vfio-pci eth1`
115 3. Mount the hugetable filsystem
117 `mount -t hugetlbfs -o pagesize=1G none /dev/hugepages`
119 Ref to http://www.dpdk.org/doc/quick-start for verifying DPDK setup.
121 4. Follow the instructions in [INSTALL.md] to install only the
122 userspace daemons and utilities (via 'make install').
123 1. First time only db creation (or clearing):
126 mkdir -p /usr/local/etc/openvswitch
127 mkdir -p /usr/local/var/run/openvswitch
128 rm /usr/local/etc/openvswitch/conf.db
129 ovsdb-tool create /usr/local/etc/openvswitch/conf.db \
130 /usr/local/share/openvswitch/vswitch.ovsschema
133 2. Start ovsdb-server
136 ovsdb-server --remote=punix:/usr/local/var/run/openvswitch/db.sock \
137 --remote=db:Open_vSwitch,Open_vSwitch,manager_options \
138 --private-key=db:Open_vSwitch,SSL,private_key \
139 --certificate=Open_vSwitch,SSL,certificate \
140 --bootstrap-ca-cert=db:Open_vSwitch,SSL,ca_cert --pidfile --detach
143 3. First time after db creation, initialize:
146 ovs-vsctl --no-wait init
151 DPDK configuration arguments can be passed to vswitchd via `--dpdk`
152 argument. This needs to be first argument passed to vswitchd process.
153 dpdk arg -c is ignored by ovs-dpdk, but it is a required parameter
154 for dpdk initialization.
157 export DB_SOCK=/usr/local/var/run/openvswitch/db.sock
158 ovs-vswitchd --dpdk -c 0x1 -n 4 -- unix:$DB_SOCK --pidfile --detach
161 If allocated more than one GB hugepage (as for IVSHMEM), set amount and
162 use NUMA node 0 memory:
165 ovs-vswitchd --dpdk -c 0x1 -n 4 --socket-mem 1024,0 \
166 -- unix:$DB_SOCK --pidfile --detach
169 6. Add bridge & ports
171 To use ovs-vswitchd with DPDK, create a bridge with datapath_type
172 "netdev" in the configuration database. For example:
174 `ovs-vsctl add-br br0 -- set bridge br0 datapath_type=netdev`
176 Now you can add dpdk devices. OVS expects DPDK device names to start with
177 "dpdk" and end with a portid. vswitchd should print (in the log file) the
178 number of dpdk devices found.
181 ovs-vsctl add-port br0 dpdk0 -- set Interface dpdk0 type=dpdk
182 ovs-vsctl add-port br0 dpdk1 -- set Interface dpdk1 type=dpdk
185 Once first DPDK port is added to vswitchd, it creates a Polling thread and
186 polls dpdk device in continuous loop. Therefore CPU utilization
187 for that thread is always 100%.
189 Note: creating bonds of DPDK interfaces is slightly different to creating
190 bonds of system interfaces. For DPDK, the interface type must be explicitly
194 ovs-vsctl add-bond br0 dpdkbond dpdk0 dpdk1 -- set Interface dpdk0 type=dpdk -- set Interface dpdk1 type=dpdk
199 Test flow script across NICs (assuming ovs in /usr/src/ovs):
204 # Move to command directory
205 cd /usr/src/ovs/utilities/
207 # Clear current flows
208 ./ovs-ofctl del-flows br0
210 # Add flows between port 1 (dpdk0) to port 2 (dpdk1)
211 ./ovs-ofctl add-flow br0 in_port=1,action=output:2
212 ./ovs-ofctl add-flow br0 in_port=2,action=output:1
215 8. Performance tuning
217 With pmd multi-threading support, OVS creates one pmd thread for each
218 numa node as default. The pmd thread handles the I/O of all DPDK
219 interfaces on the same numa node. The following two commands can be used
220 to configure the multi-threading behavior.
222 `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=<hex string>`
224 The command above asks for a CPU mask for setting the affinity of pmd
225 threads. A set bit in the mask means a pmd thread is created and pinned
226 to the corresponding CPU core. For more information, please refer to
227 `man ovs-vswitchd.conf.db`
229 `ovs-vsctl set Open_vSwitch . other_config:n-dpdk-rxqs=<integer>`
231 The command above sets the number of rx queues of each DPDK interface. The
232 rx queues are assigned to pmd threads on the same numa node in round-robin
233 fashion. For more information, please refer to `man ovs-vswitchd.conf.db`
235 Ideally for maximum throughput, the pmd thread should not be scheduled out
236 which temporarily halts its execution. The following affinitization methods
239 Lets pick core 4,6,8,10 for pmd threads to run on. Also assume a dual 8 core
240 sandy bridge system with hyperthreading enabled where CPU1 has cores 0,...,7
241 and 16,...,23 & CPU2 cores 8,...,15 & 24,...,31. (A different cpu
242 configuration could have different core mask requirements).
244 To kernel bootline add core isolation list for cores and associated hype cores
245 (e.g. isolcpus=4,20,6,22,8,24,10,26,). Reboot system for isolation to take
246 effect, restart everything.
248 Configure pmd threads on core 4,6,8,10 using 'pmd-cpu-mask':
250 `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=00000550`
252 You should be able to check that pmd threads are pinned to the correct cores
256 top -p `pidof ovs-vswitchd` -H -d1
259 Note, the pmd threads on a numa node are only created if there is at least
260 one DPDK interface from the numa node that has been added to OVS.
262 To understand where most of the time is spent and whether the caches are
263 effective, these commands can be used:
266 ovs-appctl dpif-netdev/pmd-stats-clear #To reset statistics
267 ovs-appctl dpif-netdev/pmd-stats-show
273 Following the steps above to create a bridge, you can now add dpdk rings
274 as a port to the vswitch. OVS will expect the DPDK ring device name to
275 start with dpdkr and end with a portid.
277 `ovs-vsctl add-port br0 dpdkr0 -- set Interface dpdkr0 type=dpdkr`
279 DPDK rings client test application
281 Included in the test directory is a sample DPDK application for testing
282 the rings. This is from the base dpdk directory and modified to work
283 with the ring naming used within ovs.
285 location tests/ovs_client
290 cd /usr/src/ovs/tests/
291 ovsclient -c 1 -n 4 --proc-type=secondary -- -n "port id you gave dpdkr"
294 In the case of the dpdkr example above the "port id you gave dpdkr" is 0.
296 It is essential to have --proc-type=secondary
298 The application simply receives an mbuf on the receive queue of the
299 ethernet ring and then places that same mbuf on the transmit ring of
300 the ethernet ring. It is a trivial loopback application.
302 DPDK rings in VM (IVSHMEM shared memory communications)
303 -------------------------------------------------------
305 In addition to executing the client in the host, you can execute it within
306 a guest VM. To do so you will need a patched qemu. You can download the
307 patch and getting started guide at :
309 https://01.org/packet-processing/downloads
311 A general rule of thumb for better performance is that the client
312 application should not be assigned the same dpdk core mask "-c" as
318 DPDK 2.0 supports two types of vhost:
323 Whatever type of vhost is enabled in the DPDK build specified, is the type
324 that will be enabled in OVS. By default, vhost-user is enabled in DPDK.
325 Therefore, unless vhost-cuse has been enabled in DPDK, vhost-user ports
326 will be enabled in OVS.
327 Please note that support for vhost-cuse is intended to be deprecated in OVS
333 The following sections describe the use of vhost-user 'dpdkvhostuser' ports
336 DPDK vhost-user Prerequisites:
337 -------------------------
339 1. DPDK 2.0 with vhost support enabled as documented in the "Building and
342 2. QEMU version v2.1.0+
344 QEMU v2.1.0 will suffice, but it is recommended to use v2.2.0 if providing
345 your VM with memory greater than 1GB due to potential issues with memory
346 mapping larger areas.
348 Adding DPDK vhost-user ports to the Switch:
349 --------------------------------------
351 Following the steps above to create a bridge, you can now add DPDK vhost-user
352 as a port to the vswitch. Unlike DPDK ring ports, DPDK vhost-user ports can
353 have arbitrary names.
355 - For vhost-user, the name of the port type is `dpdkvhostuser`
358 ovs-vsctl add-port br0 vhost-user-1 -- set Interface vhost-user-1
362 This action creates a socket located at
363 `/usr/local/var/run/openvswitch/vhost-user-1`, which you must provide
364 to your VM on the QEMU command line. More instructions on this can be
365 found in the next section "DPDK vhost-user VM configuration"
366 Note: If you wish for the vhost-user sockets to be created in a
367 directory other than `/usr/local/var/run/openvswitch`, you may specify
368 another location on the ovs-vswitchd command line like so:
370 `./vswitchd/ovs-vswitchd --dpdk -vhost_sock_dir /my-dir -c 0x1 ...`
372 DPDK vhost-user VM configuration:
373 ---------------------------------
374 Follow the steps below to attach vhost-user port(s) to a VM.
376 1. Configure sockets.
377 Pass the following parameters to QEMU to attach a vhost-user device:
380 -chardev socket,id=char1,path=/usr/local/var/run/openvswitch/vhost-user-1
381 -netdev type=vhost-user,id=mynet1,chardev=char1,vhostforce
382 -device virtio-net-pci,mac=00:00:00:00:00:01,netdev=mynet1
385 ...where vhost-user-1 is the name of the vhost-user port added
387 Repeat the above parameters for multiple devices, changing the
388 chardev path and id as necessary. Note that a separate and different
389 chardev path needs to be specified for each vhost-user device. For
390 example you have a second vhost-user port named 'vhost-user-2', you
391 append your QEMU command line with an additional set of parameters:
394 -chardev socket,id=char2,path=/usr/local/var/run/openvswitch/vhost-user-2
395 -netdev type=vhost-user,id=mynet2,chardev=char2,vhostforce
396 -device virtio-net-pci,mac=00:00:00:00:00:02,netdev=mynet2
399 2. Configure huge pages.
400 QEMU must allocate the VM's memory on hugetlbfs. vhost-user ports access
401 a virtio-net device's virtual rings and packet buffers mapping the VM's
402 physical memory on hugetlbfs. To enable vhost-user ports to map the VM's
403 memory into their process address space, pass the following paramters
407 -object memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages,
409 -numa node,memdev=mem -mem-prealloc
415 The following sections describe the use of vhost-cuse 'dpdkvhostcuse' ports
418 DPDK vhost-cuse Prerequisites:
419 -------------------------
421 1. DPDK 2.0 with vhost support enabled as documented in the "Building and
423 As an additional step, you must enable vhost-cuse in DPDK by setting the
424 following additional flag in `config/common_linuxapp`:
426 `CONFIG_RTE_LIBRTE_VHOST_USER=n`
428 Following this, rebuild DPDK as per the instructions in the "Building and
429 Installing" section. Finally, rebuild OVS as per step 3 in the "Building
430 and Installing" section - OVS will detect that DPDK has vhost-cuse libraries
431 compiled and in turn will enable support for it in the switch and disable
434 2. Insert the Cuse module:
438 3. Build and insert the `eventfd_link` module:
441 cd $DPDK_DIR/lib/librte_vhost/eventfd_link/
443 insmod $DPDK_DIR/lib/librte_vhost/eventfd_link.ko
446 4. QEMU version v2.1.0+
448 vhost-cuse will work with QEMU v2.1.0 and above, however it is recommended to
449 use v2.2.0 if providing your VM with memory greater than 1GB due to potential
450 issues with memory mapping larger areas.
451 Note: QEMU v1.6.2 will also work, with slightly different command line parameters,
452 which are specified later in this document.
454 Adding DPDK vhost-cuse ports to the Switch:
455 --------------------------------------
457 Following the steps above to create a bridge, you can now add DPDK vhost-cuse
458 as a port to the vswitch. Unlike DPDK ring ports, DPDK vhost-cuse ports can have
461 - For vhost-cuse, the name of the port type is `dpdkvhostcuse`
464 ovs-vsctl add-port br0 vhost-cuse-1 -- set Interface vhost-cuse-1
468 When attaching vhost-cuse ports to QEMU, the name provided during the
469 add-port operation must match the ifname parameter on the QEMU command
470 line. More instructions on this can be found in the next section.
472 DPDK vhost-cuse VM configuration:
473 ---------------------------------
475 vhost-cuse ports use a Linux* character device to communicate with QEMU.
476 By default it is set to `/dev/vhost-net`. It is possible to reuse this
477 standard device for DPDK vhost, which makes setup a little simpler but it
478 is better practice to specify an alternative character device in order to
479 avoid any conflicts if kernel vhost is to be used in parallel.
481 1. This step is only needed if using an alternative character device.
483 The new character device filename must be specified on the vswitchd
486 `./vswitchd/ovs-vswitchd --dpdk --cuse_dev_name my-vhost-net -c 0x1 ...`
488 Note that the `--cuse_dev_name` argument and associated string must be the first
489 arguments after `--dpdk` and come before the EAL arguments. In the example
490 above, the character device to be used will be `/dev/my-vhost-net`.
492 2. This step is only needed if reusing the standard character device. It will
493 conflict with the kernel vhost character device so the user must first
496 `rm -rf /dev/vhost-net`
498 3a. Configure virtio-net adaptors:
499 The following parameters must be passed to the QEMU binary:
502 -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on
503 -device virtio-net-pci,netdev=net1,mac=<mac>
506 Repeat the above parameters for multiple devices.
508 The DPDK vhost library will negiotiate its own features, so they
509 need not be passed in as command line params. Note that as offloads are
510 disabled this is the equivalent of setting:
512 `csum=off,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off`
514 3b. If using an alternative character device. It must be also explicitly
515 passed to QEMU using the `vhostfd` argument:
518 -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on,
520 -device virtio-net-pci,netdev=net1,mac=<mac>
523 The open file descriptor must be passed to QEMU running as a child
524 process. This could be done with a simple python script.
528 fd = os.open("/dev/usvhost", os.O_RDWR)
529 subprocess.call("qemu-system-x86_64 .... -netdev tap,id=vhostnet0,\
530 vhost=on,vhostfd=" + fd +"...", shell=True)
532 Alternatively the `qemu-wrap.py` script can be used to automate the
533 requirements specified above and can be used in conjunction with libvirt if
534 desired. See the "DPDK vhost VM configuration with QEMU wrapper" section
537 4. Configure huge pages:
538 QEMU must allocate the VM's memory on hugetlbfs. Vhost ports access a
539 virtio-net device's virtual rings and packet buffers mapping the VM's
540 physical memory on hugetlbfs. To enable vhost-ports to map the VM's
541 memory into their process address space, pass the following parameters
544 `-object memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages,
545 share=on -numa node,memdev=mem -mem-prealloc`
547 Note: For use with an earlier QEMU version such as v1.6.2, use the
548 following to configure hugepages instead:
550 `-mem-path /dev/hugepages -mem-prealloc`
552 DPDK vhost-cuse VM configuration with QEMU wrapper:
553 ---------------------------------------------------
554 The QEMU wrapper script automatically detects and calls QEMU with the
555 necessary parameters. It performs the following actions:
557 * Automatically detects the location of the hugetlbfs and inserts this
558 into the command line parameters.
559 * Automatically open file descriptors for each virtio-net device and
560 inserts this into the command line parameters.
561 * Calls QEMU passing both the command line parameters passed to the
562 script itself and those it has auto-detected.
564 Before use, you **must** edit the configuration parameters section of the
565 script to point to the correct emulator location and set additional
566 settings. Of these settings, `emul_path` and `us_vhost_path` **must** be
567 set. All other settings are optional.
569 To use directly from the command line simply pass the wrapper some of the
570 QEMU parameters: it will configure the rest. For example:
573 qemu-wrap.py -cpu host -boot c -hda <disk image> -m 4096 -smp 4
574 --enable-kvm -nographic -vnc none -net none -netdev tap,id=net1,
575 script=no,downscript=no,ifname=if1,vhost=on -device virtio-net-pci,
576 netdev=net1,mac=00:00:00:00:00:01
579 DPDK vhost-cuse VM configuration with libvirt:
580 ----------------------------------------------
582 If you are using libvirt, you must enable libvirt to access the character
583 device by adding it to controllers cgroup for libvirtd using the following
586 1. In `/etc/libvirt/qemu.conf` add/edit the following lines:
589 1) clear_emulator_capabilities = 0
592 4) cgroup_device_acl = [
593 "/dev/null", "/dev/full", "/dev/zero",
594 "/dev/random", "/dev/urandom",
595 "/dev/ptmx", "/dev/kvm", "/dev/kqemu",
596 "/dev/rtc", "/dev/hpet", "/dev/net/tun",
597 "/dev/<my-vhost-device>",
601 <my-vhost-device> refers to "vhost-net" if using the `/dev/vhost-net`
602 device. If you have specificed a different name on the ovs-vswitchd
603 commandline using the "--cuse_dev_name" parameter, please specify that
606 2. Disable SELinux or set to permissive mode
608 3. Restart the libvirtd process
609 For example, on Fedora:
611 `systemctl restart libvirtd.service`
613 After successfully editing the configuration, you may launch your
614 vhost-enabled VM. The XML describing the VM can be configured like so
615 within the <qemu:commandline> section:
617 1. Set up shared hugepages:
620 <qemu:arg value='-object'/>
621 <qemu:arg value='memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages,share=on'/>
622 <qemu:arg value='-numa'/>
623 <qemu:arg value='node,memdev=mem'/>
624 <qemu:arg value='-mem-prealloc'/>
627 2. Set up your tap devices:
630 <qemu:arg value='-netdev'/>
631 <qemu:arg value='type=tap,id=net1,script=no,downscript=no,ifname=vhost0,vhost=on'/>
632 <qemu:arg value='-device'/>
633 <qemu:arg value='virtio-net-pci,netdev=net1,mac=00:00:00:00:00:01'/>
636 Repeat for as many devices as are desired, modifying the id, ifname
637 and mac as necessary.
639 Again, if you are using an alternative character device (other than
640 `/dev/vhost-net`), please specify the file descriptor like so:
642 `<qemu:arg value='type=tap,id=net3,script=no,downscript=no,ifname=vhost0,vhost=on,vhostfd=<open_fd>'/>`
644 Where <open_fd> refers to the open file descriptor of the character device.
645 Instructions of how to retrieve the file descriptor can be found in the
646 "DPDK vhost VM configuration" section.
647 Alternatively, the process is automated with the qemu-wrap.py script,
648 detailed in the next section.
650 Now you may launch your VM using virt-manager, or like so:
652 `virsh create my_vhost_vm.xml`
654 DPDK vhost-cuse VM configuration with libvirt and QEMU wrapper:
655 ----------------------------------------------------------
657 To use the qemu-wrapper script in conjuntion with libvirt, follow the
658 steps in the previous section before proceeding with the following steps:
660 1. Place `qemu-wrap.py` in libvirtd's binary search PATH ($PATH)
661 Ideally in the same directory that the QEMU binary is located.
663 2. Ensure that the script has the same owner/group and file permissions
666 3. Update the VM xml file using "virsh edit VM.xml"
668 1. Set the VM to use the launch script.
669 Set the emulator path contained in the `<emulator><emulator/>` tags.
670 For example, replace:
672 `<emulator>/usr/bin/qemu-kvm<emulator/>`
676 `<emulator>/usr/bin/qemu-wrap.py<emulator/>`
678 4. Edit the Configuration Parameters section of the script to point to
679 the correct emulator location and set any additional options. If you are
680 using a alternative character device name, please set "us_vhost_path" to the
681 location of that device. The script will automatically detect and insert
682 the correct "vhostfd" value in the QEMU command line arguments.
684 5. Use virt-manager to launch the VM
686 Running ovs-vswitchd with DPDK backend inside a VM
687 --------------------------------------------------
689 Please note that additional configuration is required if you want to run
690 ovs-vswitchd with DPDK backend inside a QEMU virtual machine. Ovs-vswitchd
691 creates separate DPDK TX queues for each CPU core available. This operation
692 fails inside QEMU virtual machine because, by default, VirtIO NIC provided
693 to the guest is configured to support only single TX queue and single RX
694 queue. To change this behavior, you need to turn on 'mq' (multiqueue)
695 property of all virtio-net-pci devices emulated by QEMU and used by DPDK.
696 You may do it manually (by changing QEMU command line) or, if you use Libvirt,
697 by adding the following string:
699 `<driver name='vhost' queues='N'/>`
701 to <interface> sections of all network devices used by DPDK. Parameter 'N'
702 determines how many queues can be used by the guest.
707 - Work with 1500 MTU, needs few changes in DPDK lib to fix this issue.
708 - Currently DPDK port does not make use any offload functionality.
709 - DPDK-vHost support works with 1G huge pages.
712 - If you run Open vSwitch with smaller page sizes (e.g. 2MB), you may be
713 unable to share any rings or mempools with a virtual machine.
714 This is because the current implementation of ivshmem works by sharing
715 a single 1GB huge page from the host operating system to any guest
716 operating system through the Qemu ivshmem device. When using smaller
717 page sizes, multiple pages may be required to hold the ring descriptors
718 and buffer pools. The Qemu ivshmem device does not allow you to share
719 multiple file descriptors to the guest operating system. However, if you
720 want to share dpdkr rings with other processes on the host, you can do
721 this with smaller page sizes.
723 Platform and Network Interface:
724 - Currently it is not possible to use an Intel XL710 Network Interface as a
725 DPDK port type on a platform with more than 64 logical cores. This is
726 related to how DPDK reports the number of TX queues that may be used by
727 a DPDK application with an XL710. The maximum number of TX queues supported
728 by a DPDK application for an XL710 is 64. If a user attempts to add an
729 XL710 interface as a DPDK port type to a system as described above the
730 port addition will fail as OVS will attempt to initialize a TX queue greater
731 than 64. This issue is expected to be resolved in a future DPDK release.
732 As a workaround a user can disable hyper-threading to reduce the overall
733 core count of the system to be less than or equal to 64 when using an XL710
739 Please report problems to bugs@openvswitch.org.
741 [INSTALL.userspace.md]:INSTALL.userspace.md
742 [INSTALL.md]:INSTALL.md
743 [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
744 [DPDK Docs]: http://dpdk.org/doc