doc/vhost: vhost block documentation
Add descritpion of vhost block. Change-Id: I20c36d6b249aec09db0b5665c7ea28aea5a61358 Signed-off-by: Pawel Wodkowski <pawelx.wodkowski@intel.com> Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com> Reviewed-on: https://review.gerrithub.io/364646 Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com> Reviewed-by: Paweł Niedźwiecki <pawelx.niedzwiecki@intel.com> Tested-by: Daniel Verkamp <daniel.verkamp@intel.com> Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
This commit is contained in:
Pawel Wodkowski
Daniel Verkamp
parent
b0e128db3d
commit
c0dce4a709
50
doc/vhost.md
50
doc/vhost.md
@ -3,7 +3,7 @@
|
||||
# vhost Getting Started Guide {#vhost_getting_started}
|
||||
|
||||
The Storage Performance Development Kit vhost application is named "vhost".
|
||||
This application extends SPDK to present virtio-scsi controllers to QEMU-based
|
||||
This application extends SPDK to present virtio storage controllers to QEMU-based
|
||||
VMs and process I/O submitted to devices attached to those controllers.
|
||||
|
||||
# Prerequisites {#vhost_prereqs}
|
||||
@ -35,10 +35,10 @@ Once built, the binary will be at `app/vhost/vhost`.
|
||||
|
||||
## QEMU
|
||||
|
||||
Vhost functionality is dependent on QEMU patches to enable vhost-scsi in
|
||||
userspace - those patches are currently working their way through the QEMU
|
||||
mailing list, but temporary patches to enable this functionality are available
|
||||
in the spdk branch at https://github.com/spdk/qemu.
|
||||
Vhost functionality is dependent on QEMU patches to enable virtio-scsi and
|
||||
virtio-block in userspace - those patches are currently working their way
|
||||
through the QEMU mailing list, but temporary patches to enable this
|
||||
functionality are available in the spdk branch at https://github.com/spdk/qemu.
|
||||
|
||||
# Configuration {#vhost_config}
|
||||
|
||||
@ -48,11 +48,27 @@ target. A fully documented example configuration file is located at
|
||||
`etc/spdk/vhost.conf.in`. This file defines the following:
|
||||
|
||||
### Storage Backends
|
||||
Storage backends are block devices which will be exposed as SCSI LUNs on
|
||||
devices attached to the vhost-scsi controller. SPDK supports several different
|
||||
types of storage backends, including NVMe, Linux AIO, malloc ramdisk and Ceph
|
||||
RBD. Refer to @ref bdev_getting_started for additional information on
|
||||
specifying storage backends in the configuration file.
|
||||
Storage backends are devices which will be exposed to the guest OS. In
|
||||
case of vhost block controller they are exposed as block devices, in case of
|
||||
vhost scsi as SCSI LUNs on devices attached to the vhost-scsi controller.
|
||||
SPDK supports several different types of storage backends, including NVMe,
|
||||
Linux AIO, malloc ramdisk and CephRBD. Refer to @ref bdev_getting_started for
|
||||
additional information on specifying storage backends in the configuration file.
|
||||
|
||||
### Mappings Block Controllers and Storage Backends
|
||||
The vhost target is exposing block controllers to the virtual machines.
|
||||
The device in the vhost controller is associated with an SPDK block device and
|
||||
configuration file defines those associations. The block device to Dev mapping
|
||||
is specified in the configuration file as:
|
||||
|
||||
~~~
|
||||
[VhostBlkX]
|
||||
Name vhost.X # Name of vhost socket
|
||||
Dev BackendX # "BackendX" is block device name from previous
|
||||
# sections in config file
|
||||
#Cpumask 0x1 # Optional parameter defining which core controller uses
|
||||
|
||||
~~~
|
||||
|
||||
### Mappings Between SCSI Controllers and Storage Backends
|
||||
The vhost target is exposing SCSI controllers to the virtual machines.
|
||||
@ -76,7 +92,8 @@ are specified in the configuration file as:
|
||||
Userspace vhost uses UNIX domain sockets for communication between QEMU
|
||||
and the vhost target. Each vhost controller is associated with a UNIX domain
|
||||
socket file with filename equal to the Name argument in configuration file.
|
||||
Sockets are created at current directory when starting the SPDK vhost target.
|
||||
Sockets are created at current working directory when starting the SPDK vhost
|
||||
target.
|
||||
|
||||
### Core Affinity Configuration
|
||||
Vhost target can be restricted to run on certain cores by specifying a ReactorMask.
|
||||
@ -85,7 +102,9 @@ to run vhost with cores on each socket to achieve optimal performance.
|
||||
|
||||
To specify which core each controller should use, it can be defined by optional
|
||||
Cpumask parameter in configuration file. For NUMA systems the Cpumask should
|
||||
specify cores on the same CPU socket as its associated VM.
|
||||
specify cores on the same CPU socket as its associated VM. Application will
|
||||
pick one core from ReactorMask masked by Cpumask. Cpumask must be subset of
|
||||
ReactorMask.
|
||||
|
||||
## QEMU
|
||||
|
||||
@ -94,6 +113,11 @@ Userspace vhost-scsi adds the following command line option for QEMU:
|
||||
-device vhost-user-scsi-pci,id=scsi0,chardev=char0
|
||||
~~~
|
||||
|
||||
Userspace vhost-block adds the following command line option for QEMU:
|
||||
~~~
|
||||
-device vhost-user-blk-pci,logical_block_size=4096,size=512M,chardev=char0
|
||||
~~~
|
||||
|
||||
In order to start qemu with vhost you need to specify following options:
|
||||
|
||||
- Socket, which QEMU will use for vhost communication with SPDK:
|
||||
@ -129,6 +153,8 @@ Assume that qemu and spdk are in respectively `qemu` and `spdk` directories.
|
||||
-device ide-hd,drive=disk,bootindex=0 \
|
||||
-chardev socket,id=char0,path=./spdk/vhost.0 \
|
||||
-device vhost-user-scsi-pci,id=scsi0,chardev=char0 \
|
||||
-chardev socket,id=char1,path=./spdk/vhost.1 \
|
||||
-device vhost-user-blk-pci,logical_block_size=4096,size=512M,chardev=char1 \
|
||||
--enable-kvm
|
||||
~~~
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user