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Introduction

First of all, to set some expectations to you, this blog-post does not focus on what DPDK or OpenVSwitch (OvS) are but it tries to provide the information required to have them running on a SUSE distribution. If you require detailed information about DPDK or OvS design, architecture, internals or API then please refer to either the DPDK website (http://www.dpdk.org) or the OpenVSwitch website (http://www.openvswitch.org) respectively.

DPDK

Pre-requisite

DPDK needs some requirements to be fulfilled from both a hardware and software perspective in order to function correctly:

  • IOMMU
  • Hugepages support

In order to enable the IOMMU support, it is required to edit the kernel bootstrap parameters (/etc/default/grub) and add the following:

iommu=pt intel_iommu=on

For hugepages support, different system support different hugepage sizes. For most use cases it is recommended to use a 2MB hugepage. To enable that, it is required to edit the kernel bootstrap parameters and add the following:

default_hugepagesz=2M hugepagesz=2M hugepages=1024

Once the above modifications have been applied, the following command needs to be run:

$ grub2-mkconfig -o /boot/grub2/grub.cfg

and finally reboot the machine with

$ reboot

An alternative approach to setup hugepages which works only for 2MB hugepages is the following:

$ echo 1024 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages

On NUMA machines the instructions have to be issued for each NUMA node:

$ echo 1024 > /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages
$ echo 1024 > /sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages

For further information, please visit https://doc.dpdk.org/guides/linux_gsg/sys_reqs.html

Once the machine has rebooted, please ensure that the IOMMU is enabled and working correctly by issuing:

$ dmesg | grep DMAR

The output will show a lot of information and the one confirming the IOMMU setup is

[ 0.000000] DMAR: IOMMU enabled

Similarly, before proceeding any further with installation and setup, let’s check that hugepages are available by:

$ cat /proc/meminfo |grep Huge

Depending on the number of hugepages reserved a different output might be displayed. An example is showed below:

AnonHugePages: 509952 kB
HugePages_Total: 1024
HugePages_Free: 1024
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB

Once the hugepages have been enabled they need to be made available to DPDK by mounting that memory. That can be done via:

$ mkdir /mnt/huge
$ mount -t hugetlbfs nodev /mnt/huge

In order to have the mount point persist across reboots it is required to edit the /etc/fstab and add:

nodev /mnt/huge hugetlbfs defaults 0 0

Installation & Setup

The latest and greatest openSUSE release (Leap 15) comes with DPDK 17.11.2 (http://www.dpdk.org). On the other hand, Tumbleweed (the SUSE rolling release) is offering DPDK 18.02.2.
On both distributions, to have the DPDK libraries and tools installed, you can simply type:

$ zypper install dpdk dpdk-tools

Once the installation completes, the binary dpdk-devbind (part of dpdk-tools) can be used to query the status of network interfaces and bind / unbind them to DPDK.
Different PMDs (Poll Mode Drivers) may require different kernel drivers in order to work properly. Depending on the PMD being used, a corresponding kernel driver should be loaded and binded to the network ports. Details of the different kernel drivers can be found at https://doc.dpdk.org/guides/linux_gsg/linux_drivers.html

For this post we will use the kernel driver vfio-pci which is fine in most circumstances:

$ modprobe vfio-pci

Now, as mentioned earlier we can use the dpdk-devbind binary to query and modify network interface(s) assignment:

$ dpdk-devbind.py --status
Network devices using DPDK-compatible driver
 ============================================
 0000:82:00.0 '82599EB 10-GbE NIC' drv=vfio-pci unused=ixgbe
 0000:82:00.1 '82599EB 10-GbE NIC' drv=vfio-pci unused=ixgbe

Network devices using kernel driver
 ===================================
 0000:04:00.0 'I350 1-GbE NIC' if=em0 drv=igb unused=vfio-pci *Active*
 0000:04:00.1 'I350 1-GbE NIC' if=eth1 drv=igb unused=vfio-pci
 0000:04:00.2 'I350 1-GbE NIC' if=eth2 drv=igb unused=vfio-pci
 0000:04:00.3 'I350 1-GbE NIC' if=eth3 drv=igb unused=vfio-pci

Other network devices
 =====================
 <none>

From the above output we can understand that 2 ports are managed by vfio-pci and can be used by DPDK.
At the same time, the tool informs us about which kernel driver would be capable of managing this device when not managed by DPDK. That is accomplished by the “unused” field in the command output.

To bind a port to vfio-pci hence to DPDK:

$ dpdk-devbind.py --bind=vfio-pci 0000:04:00.3

To return a port to the kernel hence unbinding it from DPDK:

$ dpdk-devbind.py --bind=ixgbe 0000:82:00.0

Ports binding is not persisted automatically across reboots so if you expect given ports to always be assigned to DPDK you need to either create some custom scripts to be managed by systemd or use driverctl to accomplish that. To install driverctl:

$ zypper install driverctl

OpenVSwitch-DPDK on openSUSE

The latest and greatest openSUSE release (Leap 15) comes with OpenVSwitch 2.8.2 whilst the SUSE rolling-release (Tumbleweed) ships 2.9.2.

Installation

In order to install OpenVSwitch via zypper the following command can be used:

$ zypper install openvswitch

The openvswitch daemon and services can be started via

$ systemctl start openvswitch

and to keep it enabled across reboots

$ systemctl enable openvswitch

Setup

By default openvswitch does not take advantage of the DPDK acceleration; to enable it ovs-vswitchd needs to be made aware of it. To do that:

$ ovs-vsctl --no-wait set Open_vSwitch . other_config:dpdk-init=true

To confirm that DPDK support has been initialized we can issue:

$ ovs-vsctl get Open_vSwitch . dpdk_initialized

If the setup is fully initialized then the output will show “true”.

Now, in order for openvswitch to use a port accelerated via DPDK that port needs to first be binded to DPDK for manageability purposes (see above).

To create a userspace bridge named br0 and add two dpdk ports to it:

$ ovs-vsctl add-br br0 -- set bridge br0 datapath_type=netdev
 $ ovs-vsctl add-port br0 myportnameone -- set Interface myportnameone \
 type=dpdk options:dpdk-devargs=0000:06:00.0
 $ ovs-vsctl add-port br0 myportnametwo -- set Interface myportnametwo \
 type=dpdk options:dpdk-devargs=0000:06:00.1

For other information specific to OpenVSwitch please see http://docs.openvswitch.org/en/latest/intro/install/dpdk/


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Category: Enterprise Linux, openSUSE, SUSE Linux Enterprise, SUSE Linux Enterprise Server, Technical Solutions
This entry was posted Tuesday, 7 August, 2018 at 7:27 am
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