Dynamic traces

Parsing arbitrary trace events

trappy knows about some trace events. You can add your own in the notebook without having to change any code in trappy. After the trace is registered, the next time you parse a trace file that information will be part of the trace object as a pandas DataFrame and can be analyzed like the other DataFrames in the FTrace class.

The trace event must follow the following format:

title: key0=value0 key1=value1 key2=value2 ...

The title should be something that's unique in the trace. For example, you can generate trace with the following trace_printk():

trace_printk("thermal_gpu_power_get: frequency=%u load=%d\n", freq, load);

which will appear in the trace.txt as:

kworker/6:1-457   [006]   144.439566: bprint:               0xc042f8a0f: thermal_gpu_power_get: frequency=177 load=0

You can add this event to the trace instance using the events argument of the FTrace class. By using scope=custom, we limit the parsing to the events we define, making parsing much faster.

In [19]:
import sys
%matplotlib inline
import trappy

Parse the trace with the events keyword

In [22]:
trace = trappy.FTrace("trace_dynamic.txt", events=["thermal_gpu_power_get"], scope="custom")

trace now has a thermal_gpu_power_get member that contains the information. We can see the first few lines of the generated dataframe:

In [25]:

__comm __cpu __line __pid frequency load
0.0 kworker/6:1 0 0 457 420 91
0.1 kworker/6:1 0 1 457 420 90
0.2 kworker/6:1 0 2 457 420 91
0.3 kworker/6:1 0 3 457 420 90
0.4 kworker/6:1 0 4 457 420 95

We can now plot it or manipulate it as any other DataFrame in pandas

In [26]:
trace.thermal_gpu_power_get.data_frame["frequency"].plot(figsize=(18, 7))

<matplotlib.axes._subplots.AxesSubplot at 0x7f79ea816da0>