1 The code in this directory is used to process data from the mmc tracepoints 2 in the kernel. To turn on mmc tracing, do this: 3 4 adb shell echo 1 >/d/tracing/events/mmc/enable 5 adb shell echo 1 >/d/tracing/tracing_on 6 7 To get the trace: 8 9 adb pull /d/tracing/trace 10 11 To turn it back off, do: 12 13 adb shell echo 0 >/d/tracing/tracing_enabled 14 15 The output is in a form of start/stop pairs. The ops with rw in the name are 16 read or write ops, and the ones with erase in the name are the various erase 17 opts. 18 19 The mmc_trace_reduce script will take the output from the kernel, and convert it 20 to a single line per event, which includes the duration of the event. 21 22 This can then be fed into other tools for further analysis. 23 24 The file mmc_trace_sample_data contains sample mmc trace data from a Nexus 10. 25 It includes read, write and discard entries. The discard entries came from 26 invoking fstrim in vold with "vdc fstrim dotrim". 27 28
