Usage Guide ​

• Usage Guide
  • Command
  • Restrictions
  • NVWA Acceleration Feature Description and Usage
  • Generated Log Information

Command ​

• nvwa help

  Prints the help information. The printed information is as follows:

  text

  NAME:
  nvwa - a tool used for openEuler kernel update.
  
  USAGE:
  nvwa [global options] command [command options] [arguments...]
  
  VERSION:
  0.1
  
  COMMANDS:
  update   specify kernel version for nvwa to update
  init     init nvwa running environment
  help, h  Shows a list of commands or help for one command
  
  GLOBAL OPTIONS:
  --help, -h     show help (default: false)
  --version, -v  print the version (default: false)

  Note that global options such as nvwa --help and nvwa --version are not supported due to parameter parsing restrictions. This problem will be resolved in later versions. To view the NVWA version installed in the system, run the rpm -qa nvwa command.

• nvwa update <kernel version>

  When the kernel is hot upgraded to a version, the NVWA searches for the kernel image and ramfs in the /boot directory. The kernel must be named in the vmlinuz-<kernel version> format, and rootfs in the initramfs-<kernel version>.img format.

  Note that the upgrade may fail. If the upgrade fails, some processes or services that are dumped will stop running.

  You can run the uname -r command to obtain the <kernel version> of the current version. You can find all existing versions in the /boot directory by referring to the format of the <kernel version>.

• nvwa init

  Clears the running information generated by NVWA and modifies the systemd configuration. This command is used to clear the running information before the NVWA is executed or after the execution fails.

Restrictions ​

1. For services that need to be saved using NVWA, you need to set StandardOutput and StandardError in the configuration. The following uses Redis as an example:

   conf

   [Unit]
   Description=Redis persistent key-value database
   After=network.target
   [Service]
   ExecStart=/usr/bin/redis-server /etc/redis.conf --supervised systemd
   Type=notify
   User=redis
   Group=redis
   RuntimeDirectory=redis
   RuntimeDirectoryMode=0755
   StandardOutput=file:/root/log1.log
   StandardError=file:/root/log2.log
   [Install]
   WantedBy=multi-user.target

2. To use the acceleration feature, you need to modify the cmdline and allocate proper memory. For details, see NVWA Acceleration Feature Description and Usage.

3. SELINUX needs to be disabled during the running process.

   Theoretically, you need to disable the NVWA service only after you run the NVWA update command and before you restart the system to restore the process. It is recommended that SELinux be disabled during the entire process.

NVWA Acceleration Feature Description and Usage ​

1. cpu park

   The cpu park command uses the kexec process to make the CPU stay busy waiting, so as to respond to the interrupt request sent by the primary core more quickly, and reduce the status changes.

   To use cpu park, you need to add "cpuparkmem=0x200000000" to cmdline. 0x200000000 is the start address of the memory that is not used by other programs. cpuparkmem occupies the memory space whose size is about 1 MB from this address.

   Note that if the memory is sufficient, it is recommended that the address range be after 4G(0x100000000). The first 4 GB is usually reserved by each system component, which is prone to conflict.

2. quick kexec

   quick kexec accelerates image loading using kexec.

   To use quick kexec, you need to enable related options in the configuration file. For more information, see Configurations.

3. pin_memory

   pin memory accelerates the storage and recovery of the CRIU.

   To use pin memory, you need to enable related options in the configuration file. For more information, see Configurations.

Generated Log Information ​

The logs generated by the kernel hot upgrade tool consist of two parts:

• Logs generated during running

  Run the service nvwa status command to view logs.

• Logs generated while retaining the running information

  The logs are stored in the process/service folder in the path specified by criu_dir.