Options:
  -a, --all             all pid (include kernel threads)
  --sort <order>        sort by <order>: rss|swap|total
  --pid <number>        output only selected pid
  --sleep <number>      sleep <number> milli second

  -H, --help        display this help and exit
  -V, --version     display version information and exit
  -X <x-options>    x options. try -X help