Building and Installing:
------------------------
-Required: DPDK 2.0
+Required: DPDK 2.2
Optional (if building with vhost-cuse): `fuse`, `fuse-devel` (`libfuse-dev`
on Debian/Ubuntu)
1. Set `$DPDK_DIR`
```
- export DPDK_DIR=/usr/src/dpdk-2.0
+ export DPDK_DIR=/usr/src/dpdk-2.2
cd $DPDK_DIR
```
`CONFIG_RTE_BUILD_COMBINE_LIBS=y`
- Update `config/common_linuxapp` so that DPDK is built with vhost
- libraries.
-
- `CONFIG_RTE_LIBRTE_VHOST=y`
-
Then run `make install` to build and install the library.
For default install without IVSHMEM:
- `make install T=x86_64-native-linuxapp-gcc`
+ `make install T=x86_64-native-linuxapp-gcc DESTDIR=install`
To include IVSHMEM (shared memory):
- `make install T=x86_64-ivshmem-linuxapp-gcc`
+ `make install T=x86_64-ivshmem-linuxapp-gcc DESTDIR=install`
For further details refer to http://dpdk.org/
`export DPDK_BUILD=$DPDK_DIR/x86_64-ivshmem-linuxapp-gcc/`
```
- cd $(OVS_DIR)/openvswitch
+ cd $(OVS_DIR)/
./boot.sh
./configure --with-dpdk=$DPDK_BUILD [CFLAGS="-g -O2 -Wno-cast-align"]
make
3. Bind network device to vfio-pci:
`$DPDK_DIR/tools/dpdk_nic_bind.py --bind=vfio-pci eth1`
-3. Mount the hugetable filsystem
+3. Mount the hugetable filesystem
`mount -t hugetlbfs -o pagesize=1G none /dev/hugepages`
`ovs-vsctl add-br br0 -- set bridge br0 datapath_type=netdev`
- Now you can add dpdk devices. OVS expect DPDK device name start with dpdk
- and end with portid. vswitchd should print (in the log file) the number
- of dpdk devices found.
+ Now you can add dpdk devices. OVS expects DPDK device names to start with
+ "dpdk" and end with a portid. vswitchd should print (in the log file) the
+ number of dpdk devices found.
```
ovs-vsctl add-port br0 dpdk0 -- set Interface dpdk0 type=dpdk
./ovs-ofctl add-flow br0 in_port=2,action=output:1
```
-8. Performance tuning
+8. QoS usage example
- With pmd multi-threading support, OVS creates one pmd thread for each
- numa node as default. The pmd thread handles the I/O of all DPDK
- interfaces on the same numa node. The following two commands can be used
- to configure the multi-threading behavior.
+ Assuming you have a vhost-user port transmitting traffic consisting of
+ packets of size 64 bytes, the following command would limit the egress
+ transmission rate of the port to ~1,000,000 packets per second:
- `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=<hex string>`
+ `ovs-vsctl set port vhost-user0 qos=@newqos -- --id=@newqos create qos
+ type=egress-policer other-config:cir=46000000 other-config:cbs=2048`
- The command above asks for a CPU mask for setting the affinity of pmd
- threads. A set bit in the mask means a pmd thread is created and pinned
- to the corresponding CPU core. For more information, please refer to
- `man ovs-vswitchd.conf.db`
+ To examine the QoS configuration of the port:
- `ovs-vsctl set Open_vSwitch . other_config:n-dpdk-rxqs=<integer>`
+ `ovs-appctl -t ovs-vswitchd qos/show vhost-user0`
- The command above sets the number of rx queues of each DPDK interface. The
- rx queues are assigned to pmd threads on the same numa node in round-robin
- fashion. For more information, please refer to `man ovs-vswitchd.conf.db`
+ To clear the QoS configuration from the port and ovsdb use the following:
- Ideally for maximum throughput, the pmd thread should not be scheduled out
- which temporarily halts its execution. The following affinitization methods
- can help.
+ `ovs-vsctl destroy QoS vhost-user0 -- clear Port vhost-user0 qos`
- Lets pick core 4,6,8,10 for pmd threads to run on. Also assume a dual 8 core
- sandy bridge system with hyperthreading enabled where CPU1 has cores 0,...,7
- and 16,...,23 & CPU2 cores 8,...,15 & 24,...,31. (A different cpu
- configuration could have different core mask requirements).
+ For more details regarding egress-policer parameters please refer to the
+ vswitch.xml.
- To kernel bootline add core isolation list for cores and associated hype cores
- (e.g. isolcpus=4,20,6,22,8,24,10,26,). Reboot system for isolation to take
- effect, restart everything.
+Performance Tuning:
+-------------------
- Configure pmd threads on core 4,6,8,10 using 'pmd-cpu-mask':
+ 1. PMD affinitization
- `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=00000550`
+ A poll mode driver (pmd) thread handles the I/O of all DPDK
+ interfaces assigned to it. A pmd thread will busy loop through
+ the assigned port/rxq's polling for packets, switch the packets
+ and send to a tx port if required. Typically, it is found that
+ a pmd thread is CPU bound, meaning that the greater the CPU
+ occupancy the pmd thread can get, the better the performance. To
+ that end, it is good practice to ensure that a pmd thread has as
+ many cycles on a core available to it as possible. This can be
+ achieved by affinitizing the pmd thread with a core that has no
+ other workload. See section 7 below for a description of how to
+ isolate cores for this purpose also.
- You should be able to check that pmd threads are pinned to the correct cores
- via:
+ The following command can be used to specify the affinity of the
+ pmd thread(s).
- ```
- top -p `pidof ovs-vswitchd` -H -d1
- ```
+ `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=<hex string>`
- Note, the pmd threads on a numa node are only created if there is at least
- one DPDK interface from the numa node that has been added to OVS.
+ By setting a bit in the mask, a pmd thread is created and pinned
+ to the corresponding CPU core. e.g. to run a pmd thread on core 1
+
+ `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=2`
+
+ For more information, please refer to the Open_vSwitch TABLE section in
+
+ `man ovs-vswitchd.conf.db`
+
+ Note, that a pmd thread on a NUMA node is only created if there is
+ at least one DPDK interface from that NUMA node added to OVS.
+
+ 2. Multiple poll mode driver threads
+
+ With pmd multi-threading support, OVS creates one pmd thread
+ for each NUMA node by default. However, it can be seen that in cases
+ where there are multiple ports/rxq's producing traffic, performance
+ can be improved by creating multiple pmd threads running on separate
+ cores. These pmd threads can then share the workload by each being
+ responsible for different ports/rxq's. Assignment of ports/rxq's to
+ pmd threads is done automatically.
+
+ The following command can be used to specify the affinity of the
+ pmd threads.
+
+ `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=<hex string>`
+
+ A set bit in the mask means a pmd thread is created and pinned
+ to the corresponding CPU core. e.g. to run pmd threads on core 1 and 2
+
+ `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=6`
+
+ For more information, please refer to the Open_vSwitch TABLE section in
+
+ `man ovs-vswitchd.conf.db`
+
+ For example, when using dpdk and dpdkvhostuser ports in a bi-directional
+ VM loopback as shown below, spreading the workload over 2 or 4 pmd
+ threads shows significant improvements as there will be more total CPU
+ occupancy available.
+
+ NIC port0 <-> OVS <-> VM <-> OVS <-> NIC port 1
+
+ The following command can be used to confirm that the port/rxq assignment
+ to pmd threads is as required:
+
+ `ovs-appctl dpif-netdev/pmd-rxq-show`
+
+ This can also be checked with:
+
+ ```
+ top -H
+ taskset -p <pid_of_pmd>
+ ```
+
+ To understand where most of the pmd thread time is spent and whether the
+ caches are being utilized, these commands can be used:
+
+ ```
+ # Clear previous stats
+ ovs-appctl dpif-netdev/pmd-stats-clear
+
+ # Check current stats
+ ovs-appctl dpif-netdev/pmd-stats-show
+ ```
+
+ 3. DPDK port Rx Queues
+
+ `ovs-vsctl set Interface <DPDK interface> options:n_rxq=<integer>`
+
+ The command above sets the number of rx queues for DPDK interface.
+ The rx queues are assigned to pmd threads on the same NUMA node in a
+ round-robin fashion. For more information, please refer to the
+ Open_vSwitch TABLE section in
+
+ `man ovs-vswitchd.conf.db`
+
+ 4. Exact Match Cache
+
+ Each pmd thread contains one EMC. After initial flow setup in the
+ datapath, the EMC contains a single table and provides the lowest level
+ (fastest) switching for DPDK ports. If there is a miss in the EMC then
+ the next level where switching will occur is the datapath classifier.
+ Missing in the EMC and looking up in the datapath classifier incurs a
+ significant performance penalty. If lookup misses occur in the EMC
+ because it is too small to handle the number of flows, its size can
+ be increased. The EMC size can be modified by editing the define
+ EM_FLOW_HASH_SHIFT in lib/dpif-netdev.c.
+
+ As mentioned above an EMC is per pmd thread. So an alternative way of
+ increasing the aggregate amount of possible flow entries in EMC and
+ avoiding datapath classifier lookups is to have multiple pmd threads
+ running. This can be done as described in section 2.
+
+ 5. Compiler options
+
+ The default compiler optimization level is '-O2'. Changing this to
+ more aggressive compiler optimizations such as '-O3' or
+ '-Ofast -march=native' with gcc can produce performance gains.
+
+ 6. Simultaneous Multithreading (SMT)
+
+ With SMT enabled, one physical core appears as two logical cores
+ which can improve performance.
+
+ SMT can be utilized to add additional pmd threads without consuming
+ additional physical cores. Additional pmd threads may be added in the
+ same manner as described in section 2. If trying to minimize the use
+ of physical cores for pmd threads, care must be taken to set the
+ correct bits in the pmd-cpu-mask to ensure that the pmd threads are
+ pinned to SMT siblings.
+
+ For example, when using 2x 10 core processors in a dual socket system
+ with HT enabled, /proc/cpuinfo will report 40 logical cores. To use
+ two logical cores which share the same physical core for pmd threads,
+ the following command can be used to identify a pair of logical cores.
+
+ `cat /sys/devices/system/cpu/cpuN/topology/thread_siblings_list`
+
+ where N is the logical core number. In this example, it would show that
+ cores 1 and 21 share the same physical core. The pmd-cpu-mask to enable
+ two pmd threads running on these two logical cores (one physical core)
+ is.
+
+ `ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=100002`
+
+ Note that SMT is enabled by the Hyper-Threading section in the
+ BIOS, and as such will apply to the whole system. So the impact of
+ enabling/disabling it for the whole system should be considered
+ e.g. If workloads on the system can scale across multiple cores,
+ SMT may very beneficial. However, if they do not and perform best
+ on a single physical core, SMT may not be beneficial.
+
+ 7. The isolcpus kernel boot parameter
+
+ isolcpus can be used on the kernel bootline to isolate cores from the
+ kernel scheduler and hence dedicate them to OVS or other packet
+ forwarding related workloads. For example a Linux kernel boot-line
+ could be:
+
+ 'GRUB_CMDLINE_LINUX_DEFAULT="quiet hugepagesz=1G hugepages=4 default_hugepagesz=1G 'intel_iommu=off' isolcpus=1-19"'
+
+ 8. NUMA/Cluster On Die
+
+ Ideally inter NUMA datapaths should be avoided where possible as packets
+ will go across QPI and there may be a slight performance penalty when
+ compared with intra NUMA datapaths. On Intel Xeon Processor E5 v3,
+ Cluster On Die is introduced on models that have 10 cores or more.
+ This makes it possible to logically split a socket into two NUMA regions
+ and again it is preferred where possible to keep critical datapaths
+ within the one cluster.
+
+ It is good practice to ensure that threads that are in the datapath are
+ pinned to cores in the same NUMA area. e.g. pmd threads and QEMU vCPUs
+ responsible for forwarding.
+
+ 9. Rx Mergeable buffers
+
+ Rx Mergeable buffers is a virtio feature that allows chaining of multiple
+ virtio descriptors to handle large packet sizes. As such, large packets
+ are handled by reserving and chaining multiple free descriptors
+ together. Mergeable buffer support is negotiated between the virtio
+ driver and virtio device and is supported by the DPDK vhost library.
+ This behavior is typically supported and enabled by default, however
+ in the case where the user knows that rx mergeable buffers are not needed
+ i.e. jumbo frames are not needed, it can be forced off by adding
+ mrg_rxbuf=off to the QEMU command line options. By not reserving multiple
+ chains of descriptors it will make more individual virtio descriptors
+ available for rx to the guest using dpdkvhost ports and this can improve
+ performance.
+
+ 10. Packet processing in the guest
+
+ It is good practice whether simply forwarding packets from one
+ interface to another or more complex packet processing in the guest,
+ to ensure that the thread performing this work has as much CPU
+ occupancy as possible. For example when the DPDK sample application
+ `testpmd` is used to forward packets in the guest, multiple QEMU vCPU
+ threads can be created. Taskset can then be used to affinitize the
+ vCPU thread responsible for forwarding to a dedicated core not used
+ for other general processing on the host system.
+
+ 11. DPDK virtio pmd in the guest
+
+ dpdkvhostcuse or dpdkvhostuser ports can be used to accelerate the path
+ to the guest using the DPDK vhost library. This library is compatible with
+ virtio-net drivers in the guest but significantly better performance can
+ be observed when using the DPDK virtio pmd driver in the guest. The DPDK
+ `testpmd` application can be used in the guest as an example application
+ that forwards packet from one DPDK vhost port to another. An example of
+ running `testpmd` in the guest can be seen here.
+
+ `./testpmd -c 0x3 -n 4 --socket-mem 512 -- --burst=64 -i --txqflags=0xf00 --disable-hw-vlan --forward-mode=io --auto-start`
+
+ See below information on dpdkvhostcuse and dpdkvhostuser ports.
+ See [DPDK Docs] for more information on `testpmd`.
- To understand where most of the time is spent and whether the caches are
- effective, these commands can be used:
- ```
- ovs-appctl dpif-netdev/pmd-stats-clear #To reset statistics
- ovs-appctl dpif-netdev/pmd-stats-show
- ```
DPDK Rings :
------------
DPDK vhost:
-----------
-DPDK 2.0 supports two types of vhost:
+DPDK 2.2 supports two types of vhost:
1. vhost-user
2. vhost-cuse
DPDK vhost-user Prerequisites:
-------------------------
-1. DPDK 2.0 with vhost support enabled as documented in the "Building and
+1. DPDK 2.2 with vhost support enabled as documented in the "Building and
Installing section"
2. QEMU version v2.1.0+
Following the steps above to create a bridge, you can now add DPDK vhost-user
as a port to the vswitch. Unlike DPDK ring ports, DPDK vhost-user ports can
-have arbitrary names.
+have arbitrary names, except that forward and backward slashes are prohibited
+in the names.
- For vhost-user, the name of the port type is `dpdkvhostuser`
```
- ovs-ofctl add-port br0 vhost-user-1 -- set Interface vhost-user-1
+ ovs-vsctl add-port br0 vhost-user-1 -- set Interface vhost-user-1
type=dpdkvhostuser
```
-numa node,memdev=mem -mem-prealloc
```
+3. Optional: Enable multiqueue support
+ The vhost-user interface must be configured in Open vSwitch with the
+ desired amount of queues with:
+
+ ```
+ ovs-vsctl set Interface vhost-user-2 options:n_rxq=<requested queues>
+ ```
+
+ QEMU needs to be configured as well.
+ The $q below should match the queues requested in OVS (if $q is more,
+ packets will not be received).
+ The $v is the number of vectors, which is '$q x 2 + 2'.
+
+ ```
+ -chardev socket,id=char2,path=/usr/local/var/run/openvswitch/vhost-user-2
+ -netdev type=vhost-user,id=mynet2,chardev=char2,vhostforce,queues=$q
+ -device virtio-net-pci,mac=00:00:00:00:00:02,netdev=mynet2,mq=on,vectors=$v
+ ```
+
+ If one wishes to use multiple queues for an interface in the guest, the
+ driver in the guest operating system must be configured to do so. It is
+ recommended that the number of queues configured be equal to '$q'.
+
+ For example, this can be done for the Linux kernel virtio-net driver with:
+
+ ```
+ ethtool -L <DEV> combined <$q>
+ ```
+
+ A note on the command above:
+
+ `-L`: Changes the numbers of channels of the specified network device
+
+ `combined`: Changes the number of multi-purpose channels.
+
DPDK vhost-cuse:
----------------
DPDK vhost-cuse Prerequisites:
-------------------------
-1. DPDK 2.0 with vhost support enabled as documented in the "Building and
+1. DPDK 2.2 with vhost support enabled as documented in the "Building and
Installing section"
As an additional step, you must enable vhost-cuse in DPDK by setting the
following additional flag in `config/common_linuxapp`:
- For vhost-cuse, the name of the port type is `dpdkvhostcuse`
```
- ovs-ofctl add-port br0 vhost-cuse-1 -- set Interface vhost-cuse-1
+ ovs-vsctl add-port br0 vhost-cuse-1 -- set Interface vhost-cuse-1
type=dpdkvhostcuse
```
subprocess.call("qemu-system-x86_64 .... -netdev tap,id=vhostnet0,\
vhost=on,vhostfd=" + fd +"...", shell=True)
- Alternatively the the `qemu-wrap.py` script can be used to automate the
+ Alternatively the `qemu-wrap.py` script can be used to automate the
requirements specified above and can be used in conjunction with libvirt if
desired. See the "DPDK vhost VM configuration with QEMU wrapper" section
below.
want to share dpdkr rings with other processes on the host, you can do
this with smaller page sizes.
+ Platform and Network Interface:
+ - By default with DPDK 2.2, a maximum of 64 TX queues can be used with an
+ Intel XL710 Network Interface on a platform with more than 64 logical
+ cores. If a user attempts to add an XL710 interface as a DPDK port type to
+ a system as described above, an error will be reported that initialization
+ failed for the 65th queue. OVS will then roll back to the previous
+ successful queue initialization and use that value as the total number of
+ TX queues available with queue locking. If a user wishes to use more than
+ 64 queues and avoid locking, then the
+ `CONFIG_RTE_LIBRTE_I40E_QUEUE_NUM_PER_PF` config parameter in DPDK must be
+ increased to the desired number of queues. Both DPDK and OVS must be
+ recompiled for this change to take effect.
+
+ vHost and QEMU v2.4.0+:
+ - For versions of QEMU v2.4.0 and later, it is currently not possible to
+ unbind more than one dpdkvhostuser port from the guest kernel driver
+ without causing the ovs-vswitchd process to crash. If this is a requirement
+ for your use case, it is recommended either to use a version of QEMU
+ between v2.2.0 and v2.3.1 (inclusive), or alternatively, to apply the
+ following patch to DPDK and rebuild:
+ http://dpdk.org/dev/patchwork/patch/7736/
+ This problem will likely be resolved in Open vSwitch at a later date, when
+ the next release of DPDK (which includes the above patch) is available and
+ integrated into OVS.
+
Bug Reporting:
--------------
projects / cascardo / ovs.git / blobdiff