I am new to linux. I am trying to use ftrace to understand linux nvme driver code flow. Based on articles in net, once my nvme device is mounted, I am issuing following commands to get the trace

  1. cd /sys/kernel/debug/tracing
  2. cat /dev/nvme0n1 > trace (sudo nvme list shows up the nvme device nvme0n1)
  3. echo nvme_queue_rq > set_graph_function (nvme_queue_rq from nvme driver is called when we issue IO )
  4. echo function_graph > current_tracer
  5. echo 1 > tracing_on
  6. nvme write /dev/nvme0n1 -s0 -c63 ( issue write cmd using nvme cli)
  7. echo 0 > tracing_on
  8. cat /dev/nvme0n1 > trace
  9. cat trace

But nothing gets appended to trace file. Is there anything additional I have to do to ensure the function calls are rightly captured. Is there any alternate way to capture the function calls of linux nvme driver?

Thanks in advance


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