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eRPC is a fast and general-purpose RPC library for datacenter networks. Our NSDI 2019 paper describes the system in detail. Documentation is available online.

Some highlights:

  • Multiple supported networks: Ethernet, InfiniBand, and RoCE
  • Low latency: 2.3 microseconds round-trip RPC latency with UDP over Ethernet
  • Performance for small 32-byte RPCs: ~10M RPCs/sec with one CPU core, 60--80M RPCs/sec with one NIC.
  • Bandwidth for large RPC: 75 Gbps on one connection (one CPU core at server and client) for 8 MB RPCs
  • Scalability: 20000 RPC sessions per server
  • End-to-end congestion control that tolerates 100-way incasts
  • Nested RPCs, and long-running background RPCs
  • A port of Raft as an example. Our 3-way replication latency is 5.3 microseconds with traditional UDP over Ethernet.


  • Toolchain: A C++11 compiler and CMake 2.8+
  • See scripts/packages/ for required software packages for your distro.
  • The latest rdma_core, preferably installed from source
  • For non-Mellanox DPDK-compatible NICs, a system-wide installation from DPDK 19.11.5 LTS sources (i.e., sudo make install T=x86_64-native-linuxapp-gcc DESTDIR=/usr). Other DPDK versions are not supported.
  • NICs: Fast (10 GbE+) NICs are needed for good performance. eRPC works best with Mellanox Ethernet and InfiniBand NICs. Any DPDK-capable NICs also work well.
  • System configuration:
    • At least 1024 huge pages on every NUMA node, and unlimited SHM limits
    • On a machine with n eRPC processes, eRPC uses kernel UDP ports {31850, ..., 31850 + n - 1}. These ports should be open on the management network. See scripts/firewalld/ for systems running firewalld.

eRPC quickstart

  • Build and run the test suite: cmake . -DPERF=OFF -DTRANSPORT=infiniband; make -j; sudo ctest.
    • DPERF=OFF enables debugging, which greatly reduces performance. Set DPERF=ON for performance measurements.
    • Here, infiniband should be replaced with raw for Mellanox Ethernet NICs, or dpdk for Intel Ethernet NICs.
    • A machine with two ports is needed to run the unit tests if DPDK is chosen. Run scripts/ instead of ctest.
  • Run the hello_world application:
    • cd hello_world
    • Edit the server and client hostnames in common.h
    • Based on the transport that eRPC was compiled for, compile hello_world using make infiniband, make raw, or make dpdk.
    • Run ./server at the server, and ./client at the client
  • Generate the documentation: doxygen

Supported bare-metal NICs:

  • Ethernet/UDP mode:
    • ConnectX-4 or newer Mellanox Ethernet NICs: Use DTRANSPORT=raw
    • DPDK-enabled NICs that support flow-director: Use DTRANSPORT=dpdk
      • Intel 82599 and Intel X710 NICs have been tested
      • raw transport is faster for Mellanox NICs, which also support DPDK
    • DPDK-enabled NICs on Microsoft Azure: Use -DTRANSPORT=dpdk -DAZURE=on
    • ConnectX-3 Ethernet NICs are supported in eRPC's RoCE mode
  • RDMA (InfiniBand/RoCE) NICs: Use DTRANSPORT=infiniband. Add DROCE=on if using RoCE.
  • Mellanox drivers optimized specially for eRPC are available in the drivers directory

Running eRPC over DPDK on Microsoft Azure VMs

  • eRPC works well on Azure VMs with accelerated networking.

  • Configure two Ubuntu 18.04 VMs as below. Use the same resource group and availability zone for both VMs.

    • Uncheck "Accelerated Networking" when launching each VM from the Azure portal (e.g., F32s-v2). For now, this VM should have just the control network (i.e., eth0) and lo interfaces.
    • Add a NIC to Azure via the Azure CLI: az network nic create --resource-group <your resource group> --name <a name for the NIC> --vnet-name <name of the VMs' virtual network> --subnet default --accelerated-networking true --subscription <Azure subscription, if any> --location <the VM's availability zone>
    • Stop the VM launched earlier, and attach the NIC created in the previous step to the VM (i.e., in "Networking" -> "Attach network interface").
    • Re-start the VM. It should have a new interface called eth1, which eRPC will use for DPDK traffic.
  • Prepare DPDK 19.11.5:

    • rdma-core must be installed from source. First, install its dependencies listed in rdma-core's README. Then, in the rdma-core directory:

      • cmake .
      • sudo make install
    • Install upstream pre-requisite libraries and modules:

      • sudo apt install make cmake g++ gcc libnuma-dev libgflags-dev numactl
      • sudo modprobe ib_uverbs
      • sudo modprobe mlx4_ib
    • Download the DPDK 19.11.5 tarball and extract it. Other DPDK versions are not supported.

    • Edit config/common_base by changing CONFIG_RTE_LIBRTE_MLX5_PMD and CONFIG_RTE_LIBRTE_MLX4_PMD to y instead of n.

    • Build and install DPDK: sudo make install T=x86_64-native-linuxapp-gcc DESTDIR=/usr

    • Create hugepages:

sudo bash -c "echo 2048 > /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages"
sudo mkdir /mnt/huge
sudo mount -t hugetlbfs nodev /mnt/huge
  • Build eRPC's library and latency benchmark:
cmake . -DTRANSPORT=dpdk -DAZURE=on
make latency
  • Create the file scripts/autorun_process_file like below. Here, do not use the IP addresses of the accelerated NIC (i.e., not of eth1).
<Public IPv4 address of VM #1> 31850 0
<Public IPv4 address of VM #2> 31850 0
  • Run the eRPC application (the latency benchmark by default):
    • At VM #1: ./scripts/ 0 0
    • At VM #2: ./scripts/ 1 0

Configuring and running the provided applications

  • The apps directory contains a suite of benchmarks and examples. The instructions below are for this suite of applications. eRPC can also be simply linked as a library instead (see hello_world/ for an example).
  • To build an application, create scripts/autorun_app_file and change its contents to one of the available directory names in apps/. See scripts/example_autorun_app_file for an example. Then generate a Makefile using cmake . -DPERF=ON -DTRANSPORT=raw/infiniband/dpdk.
  • Each application directory in apps/ contains a config file that must specify all flags defined in apps/apps_common.h. For example, num_processes specifies the total number of eRPC processes in the cluster.
  • The URIs of eRPC processes in the cluster are specified in scripts/autorun_process_file. Each line in this file must be <hostname> <management udp port> <numa_node>.
  • Run scripts/ for each process:
    • With single-CPU machines: num_processes machines are needed. Run scripts/ <i> 0 on machine i in {0, ..., num_processes - 1}.
    • With dual-CPU machines: num_machines = ceil(num_processes / 2) machines are needed. Run scripts/ <i> <i % 2> on machine i in {0, ..., num_machines - 1}.
  • To automatically run an application at all processes in scripts/autorun_process_file, run scripts/ For some applications, statistics generated in a run can be collected and processed using scripts/

Getting help

  • GitHub issues are preferred over email. Please include the following information in the issue:
    • NIC model
    • rdma_core version and DPDK version
    • Operating system


Anuj Kalia (


	Copyright 2018, Carnegie Mellon University

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