a33e0943b0
Removed the reference count from the registrations map.
Although technically supported, registering a single memory
region more than once had a lot of unhandled cases and could
easily lead to a segfault.
RDMA maps require all memory to be unregistered in the same
chunks the memory was registered, which is often impossible
to achieve if a region was registered more than once:
1. register region 0x0 - 0x3 -> it gets mapped to
a single ibv_mr
2. register region 0x1 - 0x2 -> nothing happens, this region
is already registered
3. unregister region 0x0 - 0x3 -> 0x0-0x1 gets unregistered as
one region. 0x2-0x3 gets
unregistered as another
(leading to segfault in the
the current RDMA implementation)
The problem is that the last two regions share the same ibv_mr,
which SPDK tries to free twice. The second free causes a segfault.
vtophys map handles this case by registering each 2MB chunk
separately, but this solution cannot be applied for RDMA, as
NICs put a limitation (~2048) on the number of regions registered.
Another option is to keep a refcount of each ibv_mr allocated,
and free it only when the entire region was unregistered from the
SPDK mem map. This is however very tricky and RDMAmojo mentions
that freeing a memory buffer before unregistering its ibv_mr
may lead to a segfault.
Change-Id: I545c56e24ffa55bda211dea22aeb8a55d9631fe5
Signed-off-by: Darek Stojaczyk <dariusz.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/426085
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Storage Performance Development Kit
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
- Advanced Build Options
- 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.
./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 only been tested on MacOS and Ubuntu 16.04.2 LTS with the VirtualBox provider. The VirtualBox Extension Pack 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.
Advanced Build Options
Optional components and other build-time configuration are controlled by
settings in two Makefile fragments in the root of the repository. CONFIG
contains the base settings. Running the configure script generates a new
file, CONFIG.local, that contains overrides to the base CONFIG file. For
advanced configuration, there are a number of additional options to configure
that may be used, or CONFIG.local 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 CONFIG.local 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
default values in CONFIG and CONFIG.local. This can be useful if you, for
example, generate a CONFIG.local using the configure script and then have
one or two options (i.e. debug builds) that you wish to turn on and off
frequently.
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
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