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INSTALL.DPDK.md

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Using Open vSwitch with DPDK

Open vSwitch can use Intel(R) DPDK lib to operate entirely in userspace. This file explains how to install and use Open vSwitch in such a mode.

The DPDK support of Open vSwitch is considered experimental. It has not been thoroughly tested.

This version of Open vSwitch should be built manually with configure and make.

OVS needs a system with 1GB hugepages support.

Building and Installing:

Required DPDK 1.7

  1. Configure build & install DPDK:

  2. Set $DPDK_DIR

    export DPDK_DIR=/usr/src/dpdk-1.7.1
cd $DPDK_DIR

  3. Update config/common_linuxapp so that DPDK generate single lib file. (modification also required for IVSHMEM build)

    CONFIG_RTE_BUILD_COMBINE_LIBS=y

    Then run make install to build and isntall the library. For default install without IVSHMEM:

    make install T=x86_64-native-linuxapp-gcc

    To include IVSHMEM (shared memory):

    make install T=x86_64-ivshmem-linuxapp-gcc

    For further details refer to http://dpdk.org/

  4. Configure & build the Linux kernel:

    Refer to intel-dpdk-getting-started-guide.pdf for understanding DPDK kernel requirement.

  5. Configure & build OVS:

    • Non IVSHMEM:

      export DPDK_BUILD=$DPDK_DIR/x86_64-native-linuxapp-gcc/

    • IVSHMEM:

      export DPDK_BUILD=$DPDK_DIR/x86_64-ivshmem-linuxapp-gcc/

    cd $(OVS_DIR)/openvswitch
./boot.sh
./configure --with-dpdk=$DPDK_BUILD
make

To have better performance one can enable aggressive compiler optimizations and use the special instructions(popcnt, crc32) that may not be available on all machines. Instead of typing make, type:

make CFLAGS='-O3 -march=native'

Refer to INSTALL.userspace.md for general requirements of building userspace OVS.

Using the DPDK with ovs-vswitchd:

  1. Setup system boot Add the following options to the kernel bootline:

    default_hugepagesz=1GB hugepagesz=1G hugepages=1

  2. Setup DPDK devices:

    DPDK devices can be setup using either the VFIO (for DPDK 1.7+) or UIO modules. UIO requires inserting an out of tree driver igb_uio.ko that is available in DPDK. Setup for both methods are described below.

    • UIO:

      1. insert uio.ko: modprobe uio
      2. insert igb_uio.ko: insmod $DPDK_BUILD/kmod/igb_uio.ko
      3. Bind network device to igb_uio: $DPDK_DIR/tools/dpdk_nic_bind.py --bind=igb_uio eth1

    • VFIO:

      VFIO needs to be supported in the kernel and the BIOS. More information can be found in the DPDK Linux GSG.

      1. Insert vfio-pci.ko: modprobe vfio-pci
      2. Set correct permissions on vfio device: sudo /usr/bin/chmod a+x /dev/vfio and: sudo /usr/bin/chmod 0666 /dev/vfio/*
      3. Bind network device to vfio-pci: $DPDK_DIR/tools/dpdk_nic_bind.py --bind=vfio-pci eth1

  3. Mount the hugetable filsystem

    mount -t hugetlbfs -o pagesize=1G none /dev/hugepages

    Ref to http://www.dpdk.org/doc/quick-start for verifying DPDK setup.

  4. Follow the instructions in INSTALL.md to install only the userspace daemons and utilities (via 'make install').

    1. First time only db creation (or clearing):

      mkdir -p /usr/local/etc/openvswitch
mkdir -p /usr/local/var/run/openvswitch
rm /usr/local/etc/openvswitch/conf.db
ovsdb-tool create /usr/local/etc/openvswitch/conf.db  \
       /usr/local/share/openvswitch/vswitch.ovsschema

    2. Start ovsdb-server

      ovsdb-server --remote=punix:/usr/local/var/run/openvswitch/db.sock \
    --remote=db:Open_vSwitch,Open_vSwitch,manager_options \
    --private-key=db:Open_vSwitch,SSL,private_key \
    --certificate=Open_vSwitch,SSL,certificate \
    --bootstrap-ca-cert=db:Open_vSwitch,SSL,ca_cert --pidfile --detach

    3. First time after db creation, initialize:

      ovs-vsctl --no-wait init

  5. Start vswitchd:

    DPDK configuration arguments can be passed to vswitchd via --dpdk argument. This needs to be first argument passed to vswitchd process. dpdk arg -c is ignored by ovs-dpdk, but it is a required parameter for dpdk initialization.

    export DB_SOCK=/usr/local/var/run/openvswitch/db.sock
ovs-vswitchd --dpdk -c 0x1 -n 4 -- unix:$DB_SOCK --pidfile --detach

    If allocated more than one GB hugepage (as for IVSHMEM), set amount and use NUMA node 0 memory:

    ovs-vswitchd --dpdk -c 0x1 -n 4 --socket-mem 1024,0 \
-- unix:$DB_SOCK --pidfile --detach

  6. Add bridge & ports

    To use ovs-vswitchd with DPDK, create a bridge with datapath_type "netdev" in the configuration database. For example:

    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.

    ovs-vsctl add-port br0 dpdk0 -- set Interface dpdk0 type=dpdk
ovs-vsctl add-port br0 dpdk1 -- set Interface dpdk1 type=dpdk

    Once first DPDK port is added to vswitchd, it creates a Polling thread and polls dpdk device in continuous loop. Therefore CPU utilization for that thread is always 100%.

  7. Add test flows

    Test flow script across NICs (assuming ovs in /usr/src/ovs): Execute script:

    #! /bin/sh
# Move to command directory
cd /usr/src/ovs/utilities/

# Clear current flows
./ovs-ofctl del-flows br0

# Add flows between port 1 (dpdk0) to port 2 (dpdk1)
./ovs-ofctl add-flow br0 in_port=1,action=output:2
./ovs-ofctl add-flow br0 in_port=2,action=output:1

  8. Performance tuning

    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.

    ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=<hex string>

    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

    ovs-vsctl set Open_vSwitch . other_config:n-dpdk-rxqs=<integer>

    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

    Ideally for maximum throughput, the pmd thread should not be scheduled out which temporarily halts its execution. The following affinitization methods can help.

    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).

    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.

    Configure pmd threads on core 4,6,8,10 using 'pmd-cpu-mask':

    ovs-vsctl set Open_vSwitch . other_config:pmd-cpu-mask=00000550

    You should be able to check that pmd threads are pinned to the correct cores via:

    top -p `pidof ovs-vswitchd` -H -d1

    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.

    Note, core 0 is always reserved from non-pmd threads and should never be set in the cpu mask.

DPDK Rings :

Following the steps above to create a bridge, you can now add dpdk rings as a port to the vswitch. OVS will expect the DPDK ring device name to start with dpdkr and end with a portid.

ovs-vsctl add-port br0 dpdkr0 -- set Interface dpdkr0 type=dpdkr

DPDK rings client test application

Included in the test directory is a sample DPDK application for testing the rings. This is from the base dpdk directory and modified to work with the ring naming used within ovs.

location tests/ovs_client

To run the client :

cd /usr/src/ovs/tests/
ovsclient -c 1 -n 4 --proc-type=secondary -- -n "port id you gave dpdkr"

In the case of the dpdkr example above the "port id you gave dpdkr" is 0.

It is essential to have --proc-type=secondary

The application simply receives an mbuf on the receive queue of the ethernet ring and then places that same mbuf on the transmit ring of the ethernet ring. It is a trivial loopback application.

DPDK rings in VM (IVSHMEM shared memory communications)

In addition to executing the client in the host, you can execute it within a guest VM. To do so you will need a patched qemu. You can download the patch and getting started guide at :

https://01.org/packet-processing/downloads

A general rule of thumb for better performance is that the client application should not be assigned the same dpdk core mask "-c" as the vswitchd.

Restrictions:

  • This Support is for Physical NIC. I have tested with Intel NIC only.
  • Work with 1500 MTU, needs few changes in DPDK lib to fix this issue.
  • Currently DPDK port does not make use any offload functionality.

ivshmem:

  • The shared memory is currently restricted to the use of a 1GB huge pages.
  • All huge pages are shared amongst the host, clients, virtual machines etc.

Bug Reporting:

Please report problems to [email protected].