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Efficient RPCs for fast networks
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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. Install exactly one of the following, mutually-incompatible packages:
    • Mellanox OFED for Mellanox NICs
    • System-wide DPDK for other, DPDK-compatible NICs
  • NICs: Fast (10 GbE+) bare-metal NICs are needed for good performance. eRPC works best with Mellanox Ethernet and InfiniBand NICs. Any DPDK-capable NICs also work well. Slower/virtual NICs can still be used for testing and development.
  • 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-compatible NICs that support flow-director: Use DTRANSPORT=dpdk
      • Intel 82599 and Intel X710 NICs have been tested
      • Virtual NICs have not been tested
      • raw transport is faster for Mellanox NICs, which also support DPDK
    • 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 without fast bare-metal NICs:

  • Follow these instructions to try out eRPC on a machine without fast Mellanox or DPDK-capable NICs (e.g., on your desktop or in a virtual machine). This is for development only: eRPC is not designed to perform well in these settings. eRPC has been tested on KVM virtual machines and in Amazon EC2.
  • Create an emulated RoCE device with [SoftRoCE] (instructions soon).
  • Compile eRPC with DTRANSPORT=infiniband -DROCE=on

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
    • Mellanox OFED or DPDK version
    • Operating system


Anuj Kalia (


	Copyright 2018, Carnegie Mellon University

    Licensed under the Apache License, Version 2.0 (the "License");
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