The code in this directory is used to process data from the mmc tracepoints
in the kernel.  To turn on mmc tracing, do this:

  adb shell echo 1 >/d/tracing/events/mmc/enable
  adb shell echo 1 >/d/tracing/tracing_on

To get the trace:

  adb pull /d/tracing/trace

To turn it back off, do:

  adb shell echo 0 >/d/tracing/tracing_enabled

The output is in a form of start/stop pairs.  The ops with rw in the name are
read or write ops, and the ones with erase in the name are the various erase
opts.

The mmc_trace_reduce script will take the output from the kernel, and convert it
to a single line per event, which includes the duration of the event.

This can then be fed into other tools for further analysis.

The file mmc_trace_sample_data contains sample mmc trace data from a Nexus 10.
It includes read, write and discard entries.  The discard entries came from
invoking fstrim in vold with "vdc fstrim dotrim".