docs: Add the vhost-user-blk test doc

This doc describe how to use vhost-user-blk in Cloud Hypervisor
with SPDK. With this doc, we can setup simple test environment on
Ubuntu release.

Signed-off-by: Yang Zhong <yang.zhong@intel.com>
This commit is contained in:
Yang Zhong 2020-04-08 17:15:09 +08:00 committed by Sebastien Boeuf
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# How to test vhost-user-blk with SPDK
The purpose of this document is to illustrate how to test vhost-user-blk in Cloud Hypervisor with SPDK as the backend.
## Framework
It's a simple test to validate the block read/write between VM and block backend.
```
+----+----------+ +-------------+-----------+
| | | | | |
| |vhost-user|----------| vhost-user | dpdk |
| |blk device| | port 1 | |
| | | | | |
| +----------+ +-------------+-----------+
| | | |
| vm | | spdk |
| | | |
+--+----------------------------------------------------+--+
| | hugepages | |
| +----------------------------------------------------+ |
| |
| host |
| |
+----------------------------------------------------------+
```
## Prerequisites
Prior to running the test, the following steps need to be performed.
- Enable hugepages
- Install SPDK
Here are some good references for detailing them.
- spdk
* https://spdk.io/doc/
## Test environment
The below test environment is based on ubuntu release(16.04.1 LTS), as for other system, please check related document.
The test runs with multiple queue (MQ) support enabled, using 4 queues defined for both SPDK and the virtual machine.
Here are the details on how the test can be run.
### The hugepages settings in host linux
Add "default_hugepagesz=1G hugepagesz=1G hugepages=2" into host linux cmdline.
As for how to change Ubuntu linux cmdline in grub file, please ref below link:
https://www.ostechnix.com/configure-grub-2-boot-loader-settings-ubuntu-16-04/
reboot Ubuntu
sudo mount -t hugetlbfs -o pagesize=1G none /dev/hugepages
### Download the SPDK code
git clone https://github.com/spdk/spdk
cd spdk
git submodule update --init
### Create the build dep
./scripts/pkgdep.sh
### Build spdk
./configure
make
### Set the SPDk environment
sudo HUGEMEM=2048 scripts/setup.sh
sudo ./app/vhost/vhost -S /var/tmp -s 1024 -m 0x3 &
### Create 512M block device
sudo scripts/rpc.py bdev_malloc_create 512 512 -b Malloc0
sudo scripts/rpc.py vhost_create_blk_controller --cpumask 0x1 vhost.1 Malloc0
_Launch the VM_
VMs run in client mode. They connect to the socket created by the `dpdkvhostuser` in the SPDK backend.
```bash
# From the test terminal. We need to create one vhost-user-blk device for the --disk.
./cloud-hypervisor \
--cpus boot=4 \
--memory size=1024M,file=/dev/hugepages \
--kernel linux/arch/x86/boot/compressed/vmlinux.bin \
--cmdline "console=ttyS0 reboot=k panic=1 nomodules i8042.noaux i8042.nomux i8042.nopnp i8042.dumbkbd root=/dev/vda3 iommu=off" \
--disk "path=images/clear-kvm.img" "num_queues=4,queue_size=128,vhost_user=true,socket=/var/tmp/vhost.1,wce=true" \
--console off \
--serial tty \
--rng
```
```bash
# How to test the vhost-user-blk device with SPDK backend
login in guest
# Use lsblk command to find out vhost-user-blk device
lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
vda 253:0 0 8.5G 0 disk
├─vda1 253:1 0 511M 0 part
├─vda2 253:2 0 32M 0 part [SWAP]
└─vda3 253:3 0 8G 0 part /
vdb 253:16 0 512M 0 disk
The vhost-user-blk device is /dev/vdb
# How to do simple read/write test
dd if=/dev/vdb of=/dev/null bs=2M iflag=direct
dd of=/dev/vdb if=/dev/zero bs=2M oflag=direct count=256
If you want to do fio test, please install fio binary into guest. The detailed info is not listed here.