packet {
  ftrace_events {
    cpu: 0
    event {
      timestamp: 100
      pid: 1
      ion_stat {
        buffer_id: 123
        len: 1000
        total_allocated: 2000
      }
    }
  }
}
packet {
  ftrace_events {
    cpu: 0
    event {
      timestamp: 200
      pid: 1
      ion_stat {
        buffer_id: 123
        len: -1000
        total_allocated: 1000
      }
    }
  }
}