.. BSD LICENSE Copyright(c) 2016 Intel Corporation. All rights reserved. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of Intel Corporation nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .. _virtio_user_for_container_networking: Virtio_user for Container Networking ==================================== Container becomes more and more popular for strengths, like low overhead, fast boot-up time, and easy to deploy, etc. How to use DPDK to accelerate container networking becomes a common question for users. There are two use models of running DPDK inside containers, as shown in :numref:`figure_use_models_for_running_dpdk_in_containers`. .. _figure_use_models_for_running_dpdk_in_containers: .. figure:: img/use_models_for_running_dpdk_in_containers.* Use models of running DPDK inside container This page will only cover aggregation model. Overview -------- The virtual device, virtio-user, with unmodified vhost-user backend, is designed for high performance user space container networking or inter-process communication (IPC). The overview of accelerating container networking by virtio-user is shown in :numref:`figure_virtio_user_for_container_networking`. .. _figure_virtio_user_for_container_networking: .. figure:: img/virtio_user_for_container_networking.* Overview of accelerating container networking by virtio-user Different virtio PCI devices we usually use as a para-virtualization I/O in the context of QEMU/VM, the basic idea here is to present a kind of virtual devices, which can be attached and initialized by DPDK. The device emulation layer by QEMU in VM's context is saved by just registering a new kind of virtual device in DPDK's ether layer. And to minimize the change, we reuse already-existing virtio PMD code (driver/net/virtio/). Virtio, in essence, is a shm-based solution to transmit/receive packets. How is memory shared? In VM's case, qemu always shares the whole physical layout of VM to vhost backend. But it's not feasible for a container, as a process, to share all virtual memory regions to backend. So only those virtual memory regions (aka, hugepages initialized in DPDK) are sent to backend. It restricts that only addresses in these areas can be used to transmit or receive packets. Sample Usage ------------ Here we use Docker as container engine. It also applies to LXC, Rocket with some minor changes. #. Compile DPDK. .. code-block:: console make install RTE_SDK=`pwd` T=x86_64-native-linuxapp-gcc #. Write a Dockerfile like below. .. code-block:: console cat <> Dockerfile FROM ubuntu:latest WORKDIR /usr/src/dpdk COPY . /usr/src/dpdk ENV PATH "$PATH:/usr/src/dpdk/x86_64-native-linuxapp-gcc/app/" EOT #. Build a Docker image. .. code-block:: console docker build -t dpdk-app-testpmd . #. Start a testpmd on the host with a vhost-user port. .. code-block:: console $(testpmd) -l 0-1 -n 4 --socket-mem 1024,1024 \ --vdev 'eth_vhost0,iface=/tmp/sock0' \ --file-prefix=host --no-pci -- -i #. Start a container instance with a virtio-user port. .. code-block:: console docker run -i -t -v /tmp/sock0:/var/run/usvhost \ -v /dev/hugepages:/dev/hugepages \ dpdk-app-testpmd testpmd -l 6-7 -n 4 -m 1024 --no-pci \ --vdev=virtio_user0,path=/var/run/usvhost \ --file-prefix=container \ -- -i --txqflags=0xf00 --disable-hw-vlan Note: If we run all above setup on the host, it's a shm-based IPC. Limitations ----------- We have below limitations in this solution: * Cannot work with --huge-unlink option. As we need to reopen the hugepage file to share with vhost backend. * Cannot work with --no-huge option. Currently, DPDK uses anonymous mapping under this option which cannot be reopened to share with vhost backend. * Cannot work when there are more than VHOST_MEMORY_MAX_NREGIONS(8) hugepages. In another word, do not use 2MB hugepage so far. * Applications should not use file name like HUGEFILE_FMT ("%smap_%d"). That will bring confusion when sharing hugepage files with backend by name. * Root privilege is a must. DPDK resolves physical addresses of hugepages which seems not necessary, and some discussions are going on to remove this restriction.