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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".

Building and Installing:
------------------------

Recommended to use DPDK 1.6.

DPDK:
Set dir i.g.:   export DPDK_DIR=/usr/src/dpdk-1.6.0r2
cd $DPDK_DIR
update config/defconfig_x86_64-default-linuxapp-gcc so that dpdk generate single lib file.
CONFIG_RTE_BUILD_COMBINE_LIBS=y

make install T=x86_64-default-linuxapp-gcc
For details refer to  http://dpdk.org/

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

OVS:
cd $(OVS_DIR)/openvswitch
./boot.sh
export DPDK_BUILD=/usr/src/dpdk-1.6.0r2/x86_64-default-linuxapp-gcc
./configure --with-dpdk=$DPDK_BUILD
make

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

Using the DPDK with ovs-vswitchd:
---------------------------------

Setup system boot:
   kernel bootline, add: default_hugepagesz=1GB hugepagesz=1G hugepages=1

First setup DPDK devices:
  - insert uio.ko
    e.g. modprobe uio
  - insert igb_uio.ko
    e.g. insmod DPDK/x86_64-default-linuxapp-gcc/kmod/igb_uio.ko
  - Bind network device to ibg_uio.
    e.g. DPDK/tools/pci_unbind.py --bind=igb_uio eth1
    Alternate binding method:
     Find target Ethernet devices
      lspci -nn|grep Ethernet
     Bring Down (e.g. eth2, eth3)
      ifconfig eth2 down
      ifconfig eth3 down
     Look at current devices (e.g ixgbe devices)
      ls /sys/bus/pci/drivers/ixgbe/
      0000:02:00.0  0000:02:00.1  bind  module  new_id  remove_id  uevent  unbind
     Unbind target pci devices from current driver (e.g. 02:00.0 ...)
      echo 0000:02:00.0 > /sys/bus/pci/drivers/ixgbe/unbind
      echo 0000:02:00.1 > /sys/bus/pci/drivers/ixgbe/unbind
     Bind to target driver (e.g. igb_uio)
      echo 0000:02:00.0 > /sys/bus/pci/drivers/igb_uio/bind
      echo 0000:02:00.1 > /sys/bus/pci/drivers/igb_uio/bind
     Check binding for listed devices
      ls /sys/bus/pci/drivers/igb_uio
      0000:02:00.0  0000:02:00.1  bind  module  new_id  remove_id  uevent  unbind

Prepare system:
  - load ovs kernel module
    e.g modprobe openvswitch
  - mount hugetlbfs
    e.g. mount -t hugetlbfs -o pagesize=1G none /mnt/huge/

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

Start ovsdb-server as discussed in INSTALL doc:
  Summary e.g.:
    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
      cd $OVS_DIR
      ./ovsdb/ovsdb-tool create /usr/local/etc/openvswitch/conf.db \
        ./vswitchd/vswitch.ovsschema
    start ovsdb-server
      cd $OVS_DIR
      ./ovsdb/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=dbitch,SSL,certificate \
          --bootstrap-ca-cert=db:Open_vSwitch,SSL,ca_cert --pidfile --detach
    First time after db creation, initialize:
      cd $OVS_DIR
      ./utilities/ovs-vsctl --no-wait init

Start vswitchd:
DPDK configuration arguments can be passed to vswitchd via `--dpdk`
argument. dpdk arg -c is ignored by ovs-dpdk, but it is a required parameter
for dpdk initialization.

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

If allocated more than 1 GB huge pages, set amount and use NUMA node 0 memory:

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

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

    ovs-vsctl add-br br0
    ovs-vsctl 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 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%.

Test flow script across NICs (assuming ovs in /usr/src/ovs):
  Assume 1.1.1.1 on NIC port 1 (dpdk0)
  Assume 1.1.1.2 on NIC port 2 (dpdk1)
  Execute script:

############################# 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,dl_type=0x800,nw_src=1.1.1.1,\
nw_dst=1.1.1.2,idle_timeout=0,action=output:2
./ovs-ofctl add-flow br0 in_port=2,dl_type=0x800,nw_src=1.1.1.2,\
nw_dst=1.1.1.1,idle_timeout=0,action=output:1

######################################

Ideally for maximum throughput, the 100% task should not be scheduled out
which temporarily halts the process. The following affinitization methods will
help.

At this time all ovs-vswitchd tasks end up being affinitized to cpu core 0
but this may change. Lets pick a target core for 100% task to run on, i.e. core 7.
Also assume a dual 8 core sandy bridge system with hyperthreading enabled.
(A different cpu configuration will have different core mask requirements).

To give better ownership of 100%, isolation maybe useful.
To kernel bootline add core isolation list for core 7 and associated hype core 23
  e.g.  isolcpus=7,23
Reboot system for isolation to take effect, restart everything

List threads (and their pid) of ovs-vswitchd
  top -p `pidof ovs-vswitchd` -H -d1

Look for pmd* thread which is polling dpdk devices, this will be the 100% CPU
bound task. Using this thread pid, affinitize to core 7 (mask 0x080),
example pid 1762

taskset -p 080 1762
  pid 1762's current affinity mask: 1
  pid 1762's new affinity mask: 80

Assume that all other ovs-vswitchd threads to be on other socket 0 cores.
Affinitize the rest of the ovs-vswitchd thread ids to 0x0FF007F

taskset -p 0x0FF007F {thread pid, e.g 1738}
  pid 1738's current affinity mask: 1
  pid 1738's new affinity mask: ff007f
. . .

The core 23 is left idle, which allows core 7 to run at full rate.

Future changes may change the need for cpu core affinitization.

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 :

    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.

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.
  - vswitchd userspace datapath does affine polling thread but it is
    assumed that devices are on numa node 0. Therefore if device is
    attached to non zero numa node switching performance would be
    suboptimal.
  - There are fixed number of polling thread and fixed number of per
    device queues configured.
  - 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 bugs@openvswitch.org.