title: tracing point of /sys/kernel/debug/tracing/events/nvme
body: <p>What does the events means in <code>/sys/kernel/debug/tracing/events/nvme</code>? There are four events in this directory:</p>
  <ol>
  <li><code>nvme_async_event</code></li>
  <li><code>nvme_complete_rq</code></li>
  <li><code>nvme_setup_cmd</code></li>
  <li><code>nvme_sq</code></li>
  </ol>