Storage Performance Development Kit

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The Storage Performance Development Kit (SPDK) provides a set of tools and libraries for writing high performance, scalable, user-mode storage applications. It achieves high performance by moving all of the necessary drivers into userspace and operating in a polled mode instead of relying on interrupts, which avoids kernel context switches and eliminates interrupt handling overhead.

The development kit currently includes:

• NVMe driver
• I/OAT (DMA engine) driver
• NVMe over Fabrics target
• iSCSI target
• vhost target
• Virtio-SCSI driver

In this readme

• Documentation
• Prerequisites
• Source Code
• Build
• Unit Tests
• Vagrant
• AWS
• Advanced Build Options
• Shared libraries
• Hugepages and Device Binding
• Example Code
• Contributing

Documentation

Doxygen API documentation is available, as well as a Porting Guide for porting SPDK to different frameworks and operating systems.

Source Code

git clone https://github.com/spdk/spdk
cd spdk
git submodule update --init

Prerequisites

The dependencies can be installed automatically by scripts/pkgdep.sh. The scripts/pkgdep.sh script will automatically install the bare minimum dependencies required to build SPDK. Use --help to see information on installing dependencies for optional components

./scripts/pkgdep.sh

Build

Linux:

./configure
make

FreeBSD: Note: Make sure you have the matching kernel source in /usr/src/ and also note that CONFIG_COVERAGE option is not available right now for FreeBSD builds.

./configure
gmake

Unit Tests

./test/unit/unittest.sh

You will see several error messages when running the unit tests, but they are part of the test suite. The final message at the end of the script indicates success or failure.

Vagrant

A Vagrant setup is also provided to create a Linux VM with a virtual NVMe controller to get up and running quickly. Currently this has been tested on MacOS, Ubuntu 16.04.2 LTS and Ubuntu 18.04.3 LTS with the VirtualBox and Libvirt provider. The VirtualBox Extension Pack or [Vagrant Libvirt] (https://github.com/vagrant-libvirt/vagrant-libvirt) must also be installed in order to get the required NVMe support.

Details on the Vagrant setup can be found in the SPDK Vagrant documentation.

AWS

The following setup is known to work on AWS: Image: Ubuntu 18.04 Before running setup.sh, run modprobe vfio-pci then: DRIVER_OVERRIDE=vfio-pci ./setup.sh

Advanced Build Options

Optional components and other build-time configuration are controlled by settings in the Makefile configuration file in the root of the repository. CONFIG contains the base settings for the configure script. This script generates a new file, mk/config.mk, that contains final build settings. For advanced configuration, there are a number of additional options to configure that may be used, or mk/config.mk can simply be created and edited by hand. A description of all possible options is located in CONFIG.

Boolean (on/off) options are configured with a 'y' (yes) or 'n' (no). For example, this line of CONFIG controls whether the optional RDMA (libibverbs) support is enabled:

CONFIG_RDMA?=n

To enable RDMA, this line may be added to mk/config.mk with a 'y' instead of 'n'. For the majority of options this can be done using the configure script. For example:

./configure --with-rdma

Additionally, CONFIG options may also be overridden on the make command line:

make CONFIG_RDMA=y

Users may wish to use a version of DPDK different from the submodule included in the SPDK repository. Note, this includes the ability to build not only from DPDK sources, but also just with the includes and libraries installed via the dpdk and dpdk-devel packages. To specify an alternate DPDK installation, run configure with the --with-dpdk option. For example:

Linux:

./configure --with-dpdk=/path/to/dpdk/x86_64-native-linuxapp-gcc
make

FreeBSD:

./configure --with-dpdk=/path/to/dpdk/x86_64-native-bsdapp-clang
gmake

The options specified on the make command line take precedence over the values in mk/config.mk. This can be useful if you, for example, generate a mk/config.mk using the configure script and then have one or two options (i.e. debug builds) that you wish to turn on and off frequently.

Shared libraries

By default, the build of the SPDK yields static libraries against which the SPDK applications and examples are linked. Configure option --with-shared provides the ability to produce SPDK shared libraries, in addition to the default static ones. Use of this flag also results in the SPDK executables linked to the shared versions of libraries. SPDK shared libraries by default, are located in ./build/lib. This includes the single SPDK shared lib encompassing all of the SPDK static libs (libspdk.so) as well as individual SPDK shared libs corresponding to each of the SPDK static ones.

In order to start a SPDK app linked with SPDK shared libraries, make sure to do the following steps:

• run ldconfig specifying the directory containing SPDK shared libraries
• provide proper LD_LIBRARY_PATH

If DPDK shared libraries are used, you may also need to add DPDK shared libraries to LD_LIBRARY_PATH

Linux:

./configure --with-shared
make
ldconfig -v -n ./build/lib
LD_LIBRARY_PATH=./build/lib/:./dpdk/build/lib/ ./build/bin/spdk_tgt

Hugepages and Device Binding

Before running an SPDK application, some hugepages must be allocated and any NVMe and I/OAT devices must be unbound from the native kernel drivers. SPDK includes a script to automate this process on both Linux and FreeBSD. This script should be run as root.

sudo scripts/setup.sh

Users may wish to configure a specific memory size. Below is an example of configuring 8192MB memory.

sudo HUGEMEM=8192 scripts/setup.sh

There are a lot of other environment variables that can be set to configure setup.sh for advanced users. To see the full list, run:

scripts/setup.sh --help

Target applications

After completing the build process, SPDK target applications can be found in spdk/build/bin directory:

• nvmf_tgt - SPDK NVMe over Fabrics target presents block devices over a fabrics,
• iscsi_tgt - SPDK iSCSI target runs I/O operations remotely with TCP/IP protocol,
• vhost - A vhost target provides a local storage service as a process running on a local machine,
• spdk_tgt - combines capabilities of all three applications.

SPDK runs in a polled mode, which means it continuously checks for operation completions. This approach assures faster response than interrupt mode, but also lessens usefulness of tools like top, which only shows 100% CPU usage for SPDK assigned cores. spdk_top is a program which simulates top application and uses SPDK's JSON RPC interface to present statistics about SPDK threads, pollers and CPU cores as an interactive list.

Example Code

Example code is located in the examples directory. The examples are compiled automatically as part of the build process. Simply call any of the examples with no arguments to see the help output. You'll likely need to run the examples as a privileged user (root) unless you've done additional configuration to grant your user permission to allocate huge pages and map devices through vfio.

Contributing

For additional details on how to get more involved in the community, including contributing code and participating in discussions and other activities, please refer to spdk.io