monado性能分析系列文章索引汇总：
XR VR AR monado oculus quest pico性能分析工具综述
Monado timing frame pacing frame timing 时间点分析
monado metrics tool离线性能指标工具分析
vr ar xr monado性能分析工具 percetto编译和monado集成

作用

对安卓性能分析工具Perfetto的C代码封装，用于丰富的性能跟踪、可视化展示和分析。

注意事项

• 建议在ubuntu20环境下编译，windows会遇到各种坑
• 最大坑点：官网只给了ubuntu X86-64系统编译和运行说明，我们需要交叉编译安卓版本

TODO

• percetto库可以在monado集成运行，并单步调试，但某些配置没配置正确，导致U_TRACE_CATEGORY_IS_ENABLED(timing)返回false，记录动作未完成。
• 指标收集、可视化分析

代码库

https://github.com/olvaffe/percetto

Percetto编译

X86-64 vs AArch64

坑点：官网给出的编译文档是linux运行环境的X86-64产出，安卓需要AArch64产出

# 查看.a arch格式
readelf -h libpercetto.a | grep Machine
Machine: Advanced Micro Devices X86-64


readelf -h libaux_util.a | grep Machine
Machine: AArch64


# 查看.so arch格式
file libpercetto.so
libpercetto.so: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, BuildID[sha1]=6e2358577575be17878617ea7a60b3b9b510300b, with debug_info, not stripped


libvulkan.so: ELF 64-bit LSB shared object, ARM aarch64, version 1 (SYSV), dynamically linked, BuildID[md5/uuid]=cb2f1deac083ae64b01c17e99e69ca4e, with debug_info, not stripped

Shared library(.so) vs Static Library(.a)

坑点

1 默认产出so，导致runtime loader发现不了libpercetto.so，需要修改loader源码（不讨论）

2 产出.a文件，loader不变，修改percetto编译和打包方式（本文讨论方式）

percetto/meson.build

编译错误：werror=true，改成werror=false

project(
'percetto',
['c', 'cpp'],
version: '0.1.6',
license: 'Apache-2.0',
meson_version: '>=0.54.0',
default_options: ['buildtype=debug',
'warning_level=2',
'werror=false',
'c_std=c11',
'cpp_std=c++2a'],
)

percetto/src/meson.build

原配置是产出so文件，修改为如下产出.a文件配置

percetto_static_lib = static_library(
'percetto',
'percetto.cc',
'perfetto-port.cc',
dependencies: dep_perfetto,
cpp_args : ['-fvisibility=hidden', '-fdata-sections', '-ffunction-sections', '-Os'],
link_args : ['-Wl,--gc-sections', '-Wl,--exclude-libs,ALL'],
install : true,
)
percetto_static_dep = declare_dependency(
include_directories: '.',
link_with: percetto_static_lib,
)


atrace_static_lib = static_library(
'percetto-atrace',
'percetto-atrace.c',
dependencies: percetto_static_dep,
c_args : ['-fvisibility=hidden', '-fdata-sections', '-ffunction-sections', '-Os'],
link_args : ['-Wl,--gc-sections', '-Wl,--exclude-libs,ALL'],
install : true,
)


atrace_static_dep = declare_dependency(
include_directories: '.',
link_with: atrace_static_lib,
)
install_headers('percetto.h', 'percetto-atrace.h')
pkg = import('pkgconfig')
pkg.generate(percetto_static_lib, description : 'C API wrapper static library for perfetto')
pkg.generate(atrace_static_lib, description : 'Android ATRACE wrapper static library for percetto')

arm64交叉编译配置meson-cross-arm64.ini

根据需要准备特定交叉编译配置文件

meson-cross-arm64.ini

[binaries]
c = '/home/liuzx/Android/Sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android29-clang'
cpp = '/home/liuzx/Android/Sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android29-clang++'
ar = '/home/liuzx/Android/Sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-ar'
strip = '/home/liuzx/Android/Sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-strip'
cmake = '/usr/local/bin/cmake'
ld = '/home/liuzx/Android/Sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-ld.gold'
#pkgconfig = '/usr/bin/x86_64-pc-linux-gnu-pkg-config'
#pcap-config = ''


[properties]
skip_sanity_check = true
sys_root = '/home/liuzx/Android/Sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/linux-x86_64/sysroot'
root = '/home/liuzx/Android/Sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/aarch64-linux-android/29'


[built-in options]
c_args = ['-O2', '-pipe', '-g', '-feliminate-unused-debug-types']
c_link_args = ['-Wl,-O1', '-Wl,--hash-style=gnu', '-Wl,--as-needed']
cpp_args = ['-O2', '-pipe', '-g', '-feliminate-unused-debug-types']
cpp_link_args = ['-Wl,-O1', '-Wl,--hash-style=gnu', '-Wl,--as-needed','-llog']
#sys_root = '/home/liuzx/Android/Sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/linux-x86_64/sysroot'
#pkg_config_libdir ='/home/liuzx/Android/Sdk/ndk/21.4.7075529/prebuilt/linux-x86_64/lib/pkgconfig'
#pkg_config_libdir ='/home/liuzx/Android/Sdk/ndk/21.4.7075529/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/aarch64-linux-android/29'


[host_machine]
system = 'linux'
cpu_family = 'aarch64'
cpu = 'aarch64'
endian = 'little'


[target_machine]
system = 'linux'
cpu_family = 'aarch64'
cpu = 'armv8a'
endian = 'little'

执行交叉编译

• --cross-file meson-cross-arm64.ini 使用交叉编译配置文件
• --prefix 指定install目录

# 生成配置信息到build目录
meson setup build --cross-file meson-cross-arm64.ini --prefix ~/open_source/percetto/install/
# 编译
meson compile -C build
# .h .a安装到install指定目录
meson install -C build

多个.a文件打包成统一libpercetto.a文件

坑点：默认产出libpercetto.a和libperfetto.a两个库，monado侧默认识别libpercetto.a库，为了最小化改动monado侧代码，需要合并.a库。

# 解压.a库
ar x libpercetto.a
perfetto-port.cc.o
sdk_perfetto.cc.o


# 解压.a库
ar x libperfetto.a
sdk_perfetto.cc.o


# 重新打包成libpercetto.a
ar crsv ../libpercetto.a *.o

至此，产生可以供monado集成的.a文件和.h文件。

Monado侧重要注意事项

节约编译时间

目前percetto只交叉编译arm64版本，对应monado只产出arm64-v8a版本，否则编译失败

// monado/src/xrt/targets/openxr_android/build.gradle
ndk {
abiFilters 'arm64-v8a'
}
// armeabi-v7a: 第7代及以上的 32位ARM 处理器
// arm64-v8a: 第8代、64位ARM处理器
// armeabi: 第5代、第6代的32位ARM处理器，早期的手机在使用，现在基本很少了。
// x86: Intel 32位处理器，在平板、模拟器用得比较多。
// x86_64: Intel 64位处理器，在平板、模拟器用得比较多。

FindPercetto.cmake

设置Percetto_ROOT_DIR路径后，默认FindPercetto.cmake依然找不到so库，因此手动设置.h和.so全路径，后续优化这个问题。

set(Percetto_ROOT_DIR /home/liuzx/open_source/percetto/install/)


find_library(
Percetto_LIBRARY
NAMES percetto
PATHS ${Percetto_ROOT_DIR}
HINTS ${PC_percetto_LIBRARY_DIRS}
PATH_SUFFIXES lib)
message(STATUS "Percetto_INCLUDE_DIR before: ${Percetto_INCLUDE_DIR}")
message(STATUS "Percetto_LIBRARY before: ${Percetto_LIBRARY}")


set(Percetto_INCLUDE_DIR "${Percetto_ROOT_DIR}/include/")
set(Percetto_LIBRARY "${Percetto_ROOT_DIR}/lib/libpercetto.so")


message(STATUS "#Percetto_INCLUDE_DIR: ${Percetto_INCLUDE_DIR}")
message(STATUS "#Percetto_LIBRARY: ${Percetto_LIBRARY}")

monado/CMakeLists.txt

打开宏开关：XRT_FEATURE_TRACING OFF --> ON

option_with_deps(XRT_FEATURE_TRACING "Enable debug tracing on supported platforms" DEFAULT ON DEPENDS "XRT_HAVE_PERCETTO OR XRT_HAVE_TRACY")

monado/src/xrt/auxiliary/util/u_trace_marker.h

默认为false，没有落记录，改成true依然返回，需要进一步研究

#define U_TRACE_CATEGORY_IS_ENABLED(_) (false)

monado/src/xrt/auxiliary/util/u_trace_marker.c

手动把false改成true，需要进一步研究通过环境变量、启动参数等方式传参

DEBUG_GET_ONCE_BOOL_OPTION(tracing, "XRT_TRACING", false)

monado/src/xrt/compositor/main/comp_window_android.c

COMP_TARGET_FORCE_FAKE_DISPLAY_TIMING
改成
COMP_TARGET_USE_DISPLAY_IF_AVAILABLE

comp_target_swapchain_init_and_set_fnptrs(&w->base, COMP_TARGET_USE_DISPLAY_IF_AVAILABLE);

monado/src/xrt/target/service-lib/service_target.c

monado默认在linux环境运行时启动percetto性能记录，因此需要修改安卓服务入口

#include "util/u_metrics.h"
#include "util/u_trace_marker.h"


void
startServer()
{
std::unique_lock lock(server_mutex);
if (!server && !server_thread) {
server_thread = std::make_unique(
[&]() {
u_trace_marker_init(); // 增加代码
u_metrics_init(); // 增加代码
ipc_server_main_android(&server, signalStartupCompleteTrampoline, this);
u_metrics_close(); // 增加代码
});
}
}

TODO

经过以上步奏，代码可以运行，并且可以单步调试，但：

• 指标依然未记录
• 如何可视化查看等

参考资料：meson 交叉编译aarch64

https://blog.csdn.net/xys616/article/details/116756444

https://android.googlesource.com/platform/external/igt-gpu-tools/+/7cb599fb0e2e9fed3c1ad9adc819e478cd40ae71/meson-cross-arm64.txt

https://gensoft.pasteur.fr/docs/mesa/19.0.8/meson.html