Derived Measurements ===================== The ``DerivedMeasurements`` API provides a consistent way of performing post processing on a provided :class:`MeasurementCsv` file. Example ------- The following example shows how to use an implementation of a :class:`DerivedMeasurement` to obtain a list of calculated ``DerivedMetric``'s. .. code-block:: ipython # Import the relevant derived measurement module # in this example the derived energy module is used. In [1]: from devlib import DerivedEnergyMeasurements # Obtain a MeasurementCsv file from an instrument or create from # existing .csv file. In this example an existing csv file is used which was # created with a sampling rate of 100Hz In [2]: from devlib import MeasurementsCsv In [3]: measurement_csv = MeasurementsCsv('/example/measurements.csv', sample_rate_hz=100) # Process the file and obtain a list of the derived measurements In [4]: derived_measurements = DerivedEnergyMeasurements.process(measurement_csv) In [5]: derived_measurements Out[5]: [device_energy: 239.1854075 joules, device_power: 5.5494089227 watts] API --- Derived Measurements ~~~~~~~~~~~~~~~~~~~~ .. class:: DerivedMeasurements The ``DerivedMeasurements`` class provides an API for post-processing instrument output offline (i.e. without a connection to the target device) to generate additional metrics. .. method:: DerivedMeasurements.process(measurement_csv) Process a :class:`MeasurementsCsv`, returning a list of :class:`DerivedMetric` and/or :class:`MeasurementsCsv` objects that have been derived from the input. The exact nature and ordering of the list memebers is specific to indivial 'class'`DerivedMeasurements` implementations. .. method:: DerivedMeasurements.process_raw(\*args) Process raw output from an instrument, returnin a list :class:`DerivedMetric` and/or :class:`MeasurementsCsv` objects that have been derived from the input. The exact nature and ordering of the list memebers is specific to indivial 'class'`DerivedMeasurements` implewmentations. The arguents to this method should be paths to raw output files generated by an instrument. The number and order of expected arguments is specific to particular implmentations. Derived Metric ~~~~~~~~~~~~~~ .. class:: DerivedMetric Represents a metric derived from previously collected ``Measurement``s. Unlike, a ``Measurement``, this was not measured directly from the target. .. attribute:: DerivedMetric.name The name of the derived metric. This uniquely defines a metric -- two ``DerivedMetric`` objects with the same ``name`` represent to instances of the same metric (e.g. computed from two different inputs). .. attribute:: DerivedMetric.value The ``numeric`` value of the metric that has been computed for a particular input. .. attribute:: DerivedMetric.measurement_type The ``MeasurementType`` of the metric. This indicates which conceptual category the metric falls into, its units, and conversions to other measurement types. .. attribute:: DerivedMetric.units The units in which the metric's value is expressed. Available Derived Measurements ------------------------------- .. note:: If a method of the API is not documented for a particular implementation, that means that it s not overriden by that implementation. It is still safe to call it -- an empty list will be returned. Energy ~~~~~~ .. class:: DerivedEnergyMeasurements The ``DerivedEnergyMeasurements`` class is used to calculate average power and cumulative energy for each site if the required data is present. The calculation of cumulative energy can occur in 3 ways. If a ``site`` contains ``energy`` results, the first and last measurements are extracted and the delta calculated. If not, a ``timestamp`` channel will be used to calculate the energy from the power channel, failing back to using the sample rate attribute of the :class:`MeasurementCsv` file if timestamps are not available. If neither timestamps or a sample rate are available then an error will be raised. .. method:: DerivedEnergyMeasurements.process(measurement_csv) This will return total cumulative energy for each energy channel, and the average power for each power channel in the input CSV. The output will contain all energy metrics followed by power metrics. The ordering of both will match the ordering of channels in the input. The metrics will by named based on the sites of the coresponding channels according to the following patters: ``"_total_energy"`` and ``"_average_power"``. FPS / Rendering ~~~~~~~~~~~~~~~ .. class:: DerivedGfxInfoStats(drop_threshold=5, suffix='-fps', filename=None, outdir=None) Produces FPS (frames-per-second) and other dervied statistics from :class:`GfxInfoFramesInstrument` output. This takes several optional parameters in creation: :param drop_threshold: FPS in an application, such as a game, which this processor is primarily targeted at, cannot reasonably drop to a very low value. This is specified to this threhold. If an FPS for a frame is computed to be lower than this treshold, it will be dropped on the assumption that frame rednering was suspended by the system (e.g. when idling), or there was some sort of error, and therefore this should be used in performance calculations. defaults to ``5``. :param suffix: The name of the gerated per-frame FPS csv file will be derived from the input frames csv file by appending this suffix. This cannot be specified at the same time as a ``filename``. :param filename: As an alternative to the suffix, a complete file name for FPS csv can be specified. This cannot be used at the same time as the ``suffix``. :param outdir: By default, the FPS csv file will be placed in the same directory as the input frames csv file. This can be changed by specifying an alternate directory here .. warning:: Specifying both ``filename`` and ``oudir`` will mean that exactly the same file will be used for FPS output on each invocation of ``process()`` (even for different inputs) resulting in previous results being overwritten. .. method:: DerivedGfxInfoStats.process(measurement_csv) Process the fames csv generated by :class:`GfxInfoFramesInstrument` and returns a list containing exactly three entries: :class:`DerivedMetric`\ s ``fps`` and ``total_frames``, followed by a :class:`MeasurentCsv` containing per-frame FPSs values. .. method:: DerivedGfxInfoStats.process_raw(gfxinfo_frame_raw_file) As input, this takes a single argument, which should be the path to the raw output file of :class:`GfxInfoFramesInstrument`. The returns stats accumulated by gfxinfo. At the time of wrinting, the stats (in order) are: ``janks``, ``janks_pc`` (percentage of all frames), ``render_time_50th_ptile`` (50th percentile, or median, for time to render a frame), ``render_time_90th_ptile``, ``render_time_95th_ptile``, ``render_time_99th_ptile``, ``missed_vsync``, ``hight_input_latency``, ``slow_ui_thread``, ``slow_bitmap_uploads``, ``slow_issue_draw_commands``. Please see the `gfxinfo documentation`_ for details. .. _gfxinfo documentation: https://developer.android.com/training/testing/performance.html .. class:: DerivedSurfaceFlingerStats(drop_threshold=5, suffix='-fps', filename=None, outdir=None) Produces FPS (frames-per-second) and other dervied statistics from :class:`SurfaceFlingerFramesInstrument` output. This takes several optional parameters in creation: :param drop_threshold: FPS in an application, such as a game, which this processor is primarily targeted at, cannot reasonably drop to a very low value. This is specified to this threhold. If an FPS for a frame is computed to be lower than this treshold, it will be dropped on the assumption that frame rednering was suspended by the system (e.g. when idling), or there was some sort of error, and therefore this should be used in performance calculations. defaults to ``5``. :param suffix: The name of the gerated per-frame FPS csv file will be derived from the input frames csv file by appending this suffix. This cannot be specified at the same time as a ``filename``. :param filename: As an alternative to the suffix, a complete file name for FPS csv can be specified. This cannot be used at the same time as the ``suffix``. :param outdir: By default, the FPS csv file will be placed in the same directory as the input frames csv file. This can be changed by specifying an alternate directory here .. warning:: Specifying both ``filename`` and ``oudir`` will mean that exactly the same file will be used for FPS output on each invocation of ``process()`` (even for different inputs) resulting in previous results being overwritten. .. method:: DerivedSurfaceFlingerStats.process(measurement_csv) Process the fames csv generated by :class:`SurfaceFlingerFramesInstrument` and returns a list containing exactly three entries: :class:`DerivedMetric`\ s ``fps`` and ``total_frames``, followed by a :class:`MeasurentCsv` containing per-frame FPSs values, followed by ``janks`` ``janks_pc``, and ``missed_vsync`` metrics.