doc/nvmf: add description of virtual mode (e2d0d979) · Commits · Public Repositories / spdk

doc/nvmf/getting_started.md

+27 −3

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		@@ -134,14 +134,14 @@ To ensure the SPDK NVMe-oF target has the best performance, configure the RNICs,
		devices, and the core assigned to the NVMe-oF subsystem to all be located on the same NUMA node.
		The following parameters are used to control which CPU cores SPDK executes on:

		1. ReactorMask A hexadecimal bit mask of the CPU cores that SPDK is allowed to execute work
		ReactorMask: A hexadecimal bit mask of the CPU cores that SPDK is allowed to execute work
		items on. The ReactorMask is located in the [Global] section of the configuration file. For example,
		to assign lcores 24,25,26 and 27 to NVMe-oF work items, set the ReactorMask to:
		~~~{.sh}
		ReactorMask 0xF000000
		~~~

		2. Assign each Subsystem to a CPU core This is accomplished by specifying the "Core" value in
		Assign each Subsystem to a CPU core: This is accomplished by specifying the "Core" value in
		the [Subsystem] section of the configuration file. For example,
		to assign the Subsystems to lcores 25 and 26:
		~~~{.sh}
		@@ -161,8 +161,32 @@ Listen RDMA 192.168.100.9:4420
		Host nqn.2016-06.io.spdk:init
		NVMe 0000:86:00.0
		~~~

		SPDK executes all code for an NVMe-oF subsystem on a single thread. Different subsystems may execute
		on different threads. SPDK gives the user maximum control to determine how many CPU cores are used
		to execute subsystems. Configuring different subsystems to execute on different CPU cores prevents
		the subsystem data from being evicted from limited CPU cache space.

		# Emulating an NVMe controller {#nvmf_config_virtual_controller}

		The SPDK NVMe-oF target provides the capability to emulate an NVMe controller using a virtual
		controller. Using virtual controllers allows storage software developers to run the NVMe-oF target
		on a system that does not have NVMe devices. You can configure a virtual controller in the configuration
		file as follows:

		Create malloc LUNs: See @ref bdev_getting_started for details on creating Malloc block devices.

		Create a virtual controller: Virtual mode allows any SPDK block device to be presented as an
		NVMe-oF namespace. These block devices don't need to be NVMe devices. For example, to create a
		virtual controller for malloc LUNs named Malloc0 and Malloc1:
		~~~{.sh}
		# Virtual controller
		[Subsystem2]
		NQN nqn.2016-06.io.spdk:cnode2
		Core 0
		Mode Virtual
		Listen RDMA 192.168.2.21:4420
		Host nqn.2016-06.io.spdk:init
		SN SPDK00000000000001
		Namespace Malloc0
		Namespace Malloc1
		~~~