SWAP

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Introduction to SWAP

SWAP is a Tizen dynamic binary instrumentation tool, it allows developers to trace and profile their applications. The tool supports a number of Tizen devices and emulators and is supplied as a part of their firmware. To check if your device contains SWAP, you can check is swap-manager package installed:
$ rpm -q swap-manager
If the output looks like the following then SWAP is installed:
swap-manager-3.0-7.6.i686
So, if your device or emulator contains SWAP, you can start using it.
SWAP is located on the target device, it is responsible for gathering run time data about the developer's application. When it works it is connected with a host side tool and communicates with it in a format described at SWAP protocol (you can see it at <swap-manager>/docs/). SWAP host side tool controls SWAP execution, provides it with a profiling session options and receives gathered data. There are two SWAP host-side tools:

  • Dynamic Analyzer GUI and CLI tools provided with Tizen Studio;
  • SWAP Python console tool,  which is provided with the swap-manager (git).

SWAP contains several useful features for developers:

  • Function profiling. This feature allows the developer to trace functions of interest of his application. It is based on uprobe mechanism. The developer specifies which functions in which binary files he wants to trace and when control flow reaches one, the event related information is collected: function address, timestamp, arguments etc. is generated.
  • Profiling of OpenGL and system APIs related to memory management, file operations, network and threading. This feature provides the developer information about application's system resources usage.
  • Leak Sanitizer. This feature generates report about memory leaks in the application.
  • Context switch profiling. This feature adds data about context switching to the trace.
  • Sampling. Used for point of process execution sampling with the specified period.

SWAP high-level design

SWAP high-level design

SWAP consists of the several parts: user-space daemon, kernel modules and SWAP library.

  • SWAP kernel modules provides kprobe and uprobe functionality and sampling feature.
  • SWAP probe library is loaded at the target process memory area, used for profiling system APIs and LSan analytic without using the expensive uprobe mechanism.
  • The daemon is used for communication between SWAP and host side. It is also responsible for executing and killing applications, transferring data between kernel- and user-space, communication with the SWAP library instances at the target application's memory areas and sending gathered data to host side.

To use SWAP the developer needs SWAP Python tool on his host-side. The developer specifies application for instrumentation, runs SWAP Python tool and gets a gathered binary trace as a result of the tool's work. The developer can use Trace Parser, which is also provided within swap-manager sources, to convert binary trace to more readable and understandable formats.

SWAP Tool User Guide

SWAP tool consists of two parts: SWAP Python tool itself and Trace Parser. (the latest user guide can always be found at <swap-manager>/src/cli/swap_cli/docs/ and <swap-manager>/src/cli/trace_parser/docs/).
SWAP Python tool is a python library which implements SWAP tool host-side. It is used for interacting with SWAP daemon, located on target, you can use it if your device contains an installed version of SWAP. SWAP Python tool can be used as a part of another application or, using its example as a reference, as a standalone tool.
Trace Parser is a part of SWAP tool. It is used for parsing binary trace, gathered by System Wide Analyzer Performance (SWAP) and outputting it in a specified format. Trace Parser supports several output types:

  • text output;
  • trace as a python source file output;
  • JSON formatted output;
  • CSV formatted output.

Getting the tool

SWAP tool is provided as a part of swap-manager. To get SWAP Python tool please do the following:

  • clone swap-manager sources and checkout to tizen branch:
$ git clone git://git.tizen.org/platform/core/system/swap-manager
$ cd swap-manager && git checkout tizen

Build

To run SWAP Python tool example, the user should do the following steps:

  1. Install target application with debug flag. Applications installed without debug flag are restricted for profiling due to security reasons;
  2. Edit emulator.py according to the user's target:
    1. set proper connection type for the field type in connection dictionary;
    2. if the type is ssh, set ip and port values;
    3. add information about connection type:
      • if connection is established via sdb, set emulator, device or serial value for target field of type_info dictionary;
      • if connection is established via ssh, set SSH connection parameters for params field and SSH username for username field of type_info dictionary;
  3. Edit example_conf.py according to the target application data:
    1. set target application type to field type of app_info dictionary that is contained in app dictionary. Now only NATIVE applications are supported due to security reasons;
    2. set Tizen application ID to field id of app_info dictionary;
    3. add data about features desirable to use:
      • if the user wants to use Sampling feature, add sampling dictionary to the file and add period field in it with the desirable period of sampling;
      • if the user wants to use any of Memory profiling, File profiling, Network profiling, Thread profiling, OpenGL profiling, Context switch profiling, Leak Sanitizer features, add features list somewhere in the file and add here 'memory', 'file', 'network', 'thread', 'opengl', 'context_switch', 'lsan' values accordingly. For always profiling version of the features, add for_all for these features;
    4. add necessary user probes for the binaries of interest. To add probe on the binary do the following:
      1. add a key-value pair to function_inst dictionary that is contained in app dictionary. The key should be a string with a full path to the binary, the value should be a list;
      2. add tuple to the list;
      3. add name or address of the function of interest to the tuple as the first value. Name should be a string, address should be an integer;
      4. add string that represents function arguments to the tuple as the second value. For the information about possible values, please refer to the Config files description section;
      5. add string with a character that represents return value of the function to the tuple as the third value. For the information about possible values, please refer to the Config files description section;
  4. Change directory to the cli directory and execute example.py:
    $ cd <swap-manager>/src/cli/ && python -m example.example
  5. All artifacts of the profiling session will be placed at the specified output_dir on stop. The default <output_dir> is /tmp/outdir/. As a result of the following command, trace in human-readable format will appear in <output_dir>/trace.txt file:
$ cd <output_dir>
$ <swap-manager>/src/cli/trace_parser/bin/swap_parser -i trace.bin -o trace.txt -s session_data.json -a api_map_list -t text

For an advanced API description and additional usage examples, please refer to the SWAP Python tool API description page.