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doc/nvmf: add description of virtual mode

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Added a section that describes the steps to configure a virtual controller.
Also update the CPU core affinity section to remove the section numbers.

Change-Id: Ide519c31d8653477ea9d9b65b03fe3ea37f78e61
Signed-off-by: John Kariuki <John.K.Kariuki@intel.com>
This commit is contained in:
John Kariuki 2017-03-10 05:43:58 -07:00 committed by Daniel Verkamp
parent 50cc397d6f
commit e2d0d9799c
1 changed files with 27 additions and 3 deletions
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doc/nvmf/getting_started.md
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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
~~~