1 ================================================================================ 2 __________ .__ 3 \______ \ |__| ____ _____ _______ ___.__. 4 | | _/ | | / \ \__ \ \_ __ \ < | | 5 | | \ | | | | \ / __ \_ | | \/ \___ | 6 |______ / |__| |___| / (____ / |__| / ____| 7 \/ \/ \/ \/ 8 _________ .__ ___________ .__ 9 / _____/ |__| ________ ____ \__ ___/ ____ ____ | | 10 \_____ \ | | \___ / _/ __ \ | | / _ \ / _ \ | | 11 / \ | | / / \ ___/ | | ( <_> ) ( <_> ) | |__ 12 /_______ / |__| /_____ \ \___ > |____| \____/ \____/ |____/ 13 \/ \/ \/ 14 ================================================================================ 15 16 -------------------------------------------------------------------------------- 17 Introduction 18 -------------------------------------------------------------------------------- 19 The ever-increasing size of binaries is a problem for everybody. Increased 20 binary size means longer download times and a bigger on-disk footprint after 21 installation. Mobile devices suffer the worst, as they frequently have 22 sub-optimal connectivity and limited storage capacity. Developers currently 23 have almost no visibility into how the space in the existing binaries is 24 divided nor how their contributions change the space within those binaries. 25 The first step to reducing the size of binaries is to make the size information 26 accessible to everyone so that developers can take action. 27 28 The Binary Size Tool does the following: 29 1. Runs "nm" on a specified binary to dump the symbol table 30 2. Runs a parallel pool of "addr2line" processes to map the symbols from the 31 symbol table back to source code (way faster than running "nm -l") 32 3. Creates (and optionally saves) an intermediate file that accurately mimcs 33 (binary compatible with) the "nm" output format, with all the source code 34 mappings present 35 4. Parses, sorts and analyzes the results 36 5. Generates an HTML-based report in the specified output directory 37 38 39 -------------------------------------------------------------------------------- 40 How to Run 41 -------------------------------------------------------------------------------- 42 Running the tool is fairly simply. For the sake of this example we will 43 pretend that you are building the Content Shell APK for Android. 44 45 1. Build your product as you normally would, e.g.: 46 ninja -C out/Release -j 100 content_shell_apk 47 48 2. Build the "binary_size_tool" target from ../../build/all_android.gyp, e.g.: 49 ninja -C out/Release binary_size_tool 50 51 3. Run the tool specifying the library and the output report directory. 52 This command will run the analysis on the Content Shell native library for 53 Android using the nm/addr2line binaries from the Android NDK for ARM, 54 producing an HTML report in /tmp/report: 55 tools/binary_size/run_binary_size_analysis.py \ 56 --library out/Release/lib/libcontent_shell_content_view.so \ 57 --destdir /tmp/report \ 58 --arch android-arm 59 60 Of course, there are additional options that you can see by running the tool 61 with "--help". 62 63 This whole process takes about an hour on a modern (circa 2014) quad-core 64 machine. If you have LOTS of RAM, you can use the "--jobs" argument to 65 add more addr2line workers; doing so will *greatly* reduce the processing time 66 but will devour system memory. If you've got the horsepower, 10 workers can 67 thrash through the binary in about 5 minutes at a cost of around 60 GB of RAM. 68 69 -------------------------------------------------------------------------------- 70 Analyzing the Output 71 -------------------------------------------------------------------------------- 72 When the tool finishes its work you'll find an HTML report in the output 73 directory that you specified with "--destdir". Open the index.html file in your 74 *cough* browser of choice *cough* and have a look around. The index.html page 75 is likely to evolve over time, but will always be your starting point for 76 investigation. From here you'll find links to various views of the data such 77 as treemap visualizations, overall statistics and "top n" lists of various 78 kinds. 79 80 The report is completely standalone. No external resources are required, so the 81 report may be saved and viewed offline with no problems. 82 83 -------------------------------------------------------------------------------- 84 Caveats 85 -------------------------------------------------------------------------------- 86 The tool is not perfect and has several shortcomings: 87 88 * Not all space in the binary is accounted for. The cause is still under 89 investigation. 90 * When dealing with inlining and such, the size cost is attributed to the 91 resource in which the code gets inlined. Depending upon your goals for 92 analysis, this may be either good or bad; fundamentally, the more trickery 93 that the compiler and/or linker do, the less simple the relationship 94 between the original source and the resultant binary. 95 * The tool is partly written in Java, temporarily tying it to Android 96 purely and solely because it needs Java build logic which is only defined 97 in the Android part of the build system. The Java portions need to be 98 rewritten in Python so we can decouple from Android, or we need to find 99 an alternative (readelf, linker maps, etc) to running nm/addr2line. 100 * The Java code assumes that the library file is within a Chromium release 101 directory. This limits it to Chromium-based binaries only. 102 * The Java code has a hack to accurately identify the source of ICU data 103 within the Chromium source tree due to missing size information in the ICU 104 ASM output in some build variants. 105 * The Python script assumes that arm-based and mips-based nm/addr2line 106 binaries exist in ../../third_party/android_tools/ndk/toolchains. This is 107 true only when dealing with Android and again limits the tool to 108 Chromium-based binaries. 109 * The Python script uses build system variables to construct the classpath 110 for running the Java code. 111 * The Javascript code in the HTML report Assumes code lives in Chromium for 112 generated hyperlinks and will not hyperlink any file that starts with the 113 substring "out". 114 115 -------------------------------------------------------------------------------- 116 Feature Requests and Bug Reports 117 -------------------------------------------------------------------------------- 118 Please file bugs and feature requests here, making sure to use the label 119 "Tools-BinarySize": 120 https://code.google.com/p/chromium/issues/entry?labels=Tools-BinarySize 121 122 View all open issues here: 123 https://code.google.com/p/chromium/issues/list?can=2&q=label:Tools-BinarySize 124
