Spdk/doc/applications.md

An Overview of SPDK Applications

SPDK is primarily a development kit that delivers libraries and header files for use in other applications. However, SPDK also contains a number of applications. These applications are primarily used to test the libraries, but many are full featured and high quality. The major applications in SPDK are:

• @ref iscsi
• @ref nvmf
• @ref vhost
• SPDK Target (a unified application combining the above three)

There are also a number of tools and examples in the examples directory.

The SPDK targets are all based on a common framework so they have much in common. The framework defines a concept called a subsystem and all functionality is implemented in various subsystems. Subsystems have a unified initialization and teardown path.

Configuring SPDK Applications

Command Line Parameters

The SPDK application framework defines a set of base command line flags for all applications that use it. Specific applications may implement additional flags.

Param	Type	Default	Description
-c	string		@ref cmd_arg_config_file
-d	flag	false	disable coredump file creation
-e	integer	0x0	tracepoint group hexadecimal mask for SPDK trace buffers
-g	flag	false	force creating just one hugetlbfs file
-h	flag	false	show all available parameters and exit
-i	integer	process PID	shared memory ID
-m	CPU mask	0x1	application @ref cpu_mask
-n	integer	all channels	number of memory channels used for DPDK
-p	integer	first core in CPU mask	master (primary) core for DPDK
-q	flag	false	disable notice level logging to stderr
-r	string	/var/tmp/spdk.sock	RPC listen address
-s	integer	all hugepage memory	memory size in MB for DPDK
-u	flag	false	@ref cmd_arg_disable_pci_access.
-w	flag	false	@ref cmd_arg_deferred_initialization
-B	B:D:F		@ref cmd_arg_pci_blacklist_whitelist.
-W	B:D:F		@ref cmd_arg_pci_blacklist_whitelist.
-L	string		@ref cmd_arg_debug_log_flags
-f	string		save pid to file under given path

Configuration file

Historically, the SPDK applications were configured using a configuration file. This is still supported, but is considered deprecated in favor of JSON RPC configuration. See @ref jsonrpc for details.

Note that -c and -w cannot be used at the same time.

Deferred initialization

SPDK applications progress through a set of states beginning with STARTUP and ending with RUNTIME.

If the -w parameter is provided SPDK will pause just before starting subsystem initialization. This state is called STARTUP. The JSON RPC server is ready but only a small subsystem of commands are available to set up initialization parameters. Those parameters can't be changed after the SPDK application enters RUNTIME state. When the client finishes configuring the SPDK subsystems it needs to issue the @ref rpc_start_subsystem_init RPC command to begin the initialization process. After rpc_start_subsystem_init returns true SPDK will enter the RUNTIME state and the list of available commands becomes much larger.

To see which RPC methods are available in the current state, issue the get_rpc_methods with the parameter current set to true.

For more details see @ref jsonrpc documentation.

Disable PCI access

If SPDK is run with PCI access disabled it won't detect any PCI devices. This includes primarily NVMe and IOAT devices. Also, the VFIO and UIO kernel modules are not required in this mode.

PCI address blacklist and whitelist

Note that -B and -W cannot be used at the same time.

If a blacklist is used all devices with the provided PCI address will be ignored. If a whitelist is used only those devices will be probed. You can used -B or -W more than once to add more than one device to list.

Debug log flags

Use a comma separated list of flags or use -L all to enable all debug flags. Run SPDK application with -h to get a list of all valid flags. Debug flags are only available in debug builds of SPDK.

CPU mask

Whenever the CPU mask is mentioned it is a string in one of the following formats:

• Case insensitive hexadecimal string with or without "0x" prefix.
• Comma separated list of CPUs or list of CPU ranges. Use '-' to define range.

Example

The following CPU masks are equal and correspond to CPUs 0, 1, 2, 8, 9, 10, 11 and 12:

0x1f07
0x1F07
1f07
[0,1,2,8-12]
[0, 1, 2, 8, 9, 10, 11, 12]