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[Paper] [Video]

UDPDK is a minimal UDP stack based on DPDK for fast point-to-point communication between servers.
It runs completely in userspace, so that you can move your packets quickly without going through the cumbersome kernel stack.
Moreover, thanks to its POSIX-like API, porting existing applications to UDPDK is dead easy!1

What UDPDK is:

  • A transport-level network stack
  • A POSIX-like implementation of UDP sockets on top of DPDK
  • A framework for low-latency packet exchanging

What UDPDK is NOT:

  • A complete IP stack
  • A mechanism to interconnect large networks nodes
  • A software running on low-end consumer NICs

1Some features may be unsupported yet.

Table of Contents

Requirements

In order to use UDPDK, your machines must be equipped with DPDK-enabled NICs; these are typically found in servers, not in laptops and desktop machines. The list of hardware officially supported by DPDK is available here. Specifically, UDPDK has been developed and tested on Intel X710-DA2 with igb_uio and vfio drivers; other devices should work as long as DPDK supports them.

Install Dependencies

UDPDK requires:

  • DPDK 20.05
  • inih (any)

They are already included in this repository as submodules, so pull them:

git submodule init
git submodule update

DPDK

DPDK is the pivotal element of UDPDK. It manages the NIC and implements Ethernet.

cd dpdk/usertools
./dpdk-setup.sh

From the menu, do the following:

  1. Compile for your specific arch, usually x86_64-native-linuxapp-gcc
  2. Load the vfio module
  3. Configure hugepages (e.g. 1024M for each NUMA node)
  4. Bind the NIC to vfio driver, specifying its PCI address

⚠️ If you use the VFIO driver, then you must enable the IOMMU in your system.
To enable it, open /etc/default/grub, add the flag intel_iommu=on in GRUB_CMDLINE_LINUX_DEFAULT, then sudo update-grub and finally reboot.

inih

inih is used for convenience to parse .ini configuration files.

cd inih
meson build
cd build
ninja

Build and install UDPDK

UDPDK builds into a static library, which eventually needs to be linked with the final application.

cd udpdk
make
sudo make install

API

The API of UDPDK closely resembles that of good old BSD sockets:

int udpdk_socket(int domain, int type, int protocol);
int udpdk_bind(int s, const struct sockaddr *addr, socklen_t addrlen);
int getsockopt(int sockfd, int level, int optname, void *optval, socklen_t *optlen);
int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t *optlen);
ssize_t udpdk_sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen);
ssize_t udpdk_recvfrom(int s, void *buf, size_t len, int flags, struct sockaddr *src_addr, socklen_t *addrlen);
int udpdk_close(int s);

In addition, the following methods are required for the proper setup and teardown of DPDK internals (structures and processes):

int udpdk_init(int argc, char *argv[]);
void udpdk_interrupt(int signum);
void udpdk_cleanup(void);

Note: select() is not implemented yet

Examples

The apps/ folder contains two simple examples: a ping-pong and a pkt-gen application.

How it works

UDPDK runs in two separate processes: the primary is the one containing the application logic (i.e. where syscalls are called), while the secondary (poller) continuously polls the NIC to send and receive data. The packets are exchanged between the application and the poller through shared memory, using lockless ring queues.

Performance

We compare UDPDK against standard UDP sockets in terms of throughput and latency.

Environment

Two identical servers are connected point-to-point on a 10G interface. Their specs are:

CPU: Intel Xeon E5-2640 @2.4GHz
RAM: 64GB
OS: Ubuntu 18.04
Kernel: 4.15.0
NIC: Intel X710 DA2 10GbE
NIC driver: VFIO (DPDK) or i40e (normal sockets)

Throughput

We measure the maximum throughput achieved varying the packet size.
The latter is inclusive of the UDP, IP and MAC headers.

As shown in the picture, UDPDK is up to 18x better than traditional sockets.
It should be noted that UDPDK saturates the 10G connection, which unfortunately is all we had: a 40G inferface would make it definitely shine!

Throughput chart

Latency

We measure the latency and its jitter.
Again, UDPDK proves to be an order of magnitude better than standard sockets.

UDPDK Standard
Mean (μs) 13.92 116.57
Std (μs) 0.74 18.49

License

The code of UDPDK is released under BSD 3-Clause license.

Citing

This work has been presented at IEEE NFV-SDN 2021, the 7th IEEE Conference on Network Functions Virtualization and Software-Defined Networking. The authors are: L. Lai, G. Ara, T. Cucinotta, K. Kondepu, L. Valcarenghi.

Lai, Leonardo, et al. "Ultra-low Latency NFV Services Using DPDK" 2021 IEEE Conference on Network Function Virtualization and Software Defined Networks (NFV-SDN). IEEE, 2021.

Contributing

Everyone is more than welcome to contribute to UDPDK by implementing new features, extending existing ones or simply reporting bugs/issues.