Profiled AOT support for Android

This is based on the NuGet package found here:

https://github.com/jonathanpeppers/Mono.Profiler.Android#usage-of-the-aot-profiler

Updating Profiles

Build MAUI following the instructions at DEVELOPMENT.md. Make sure to build with --configuration=Release.

Run the Record target on each "type" of project template:

bash

./.dotnet/dotnet build src/ProfiledAot/build.proj -bl -p:App=maui
./.dotnet/dotnet build src/ProfiledAot/build.proj -bl -p:App=maui-sc
./.dotnet/dotnet build src/ProfiledAot/build.proj -bl -p:App=maui-blazor

maui is dotnet new maui
maui-sc is dotnet new maui -sc or (sample content)
maui-blazor is dotnet new maui-blazor

You can also use -r android-x64, if you'd prefer an x86_64 emulator.

maui.aotprofile.txt and maui-blazor.aotprofile.txt are a list of method names contained within the profiles. We don't ship these, but we can use them to track changes over time. Note that they are not always in order, so I opened the files in VS Code and did Ctrl+Shift+P to get the command palette. Then Sort lines ascending to get them in alphabetical order. If the text files don't change, it is likely not necessary to update the .aotprofile files.

Testing Profiles

Once you've updated the profile, always test to make sure the times you get are either "the same" or slightly better than before.

Build MAUI again with --configuration=Release (see DEVELOPMENT.md).

Create a new project and run it:

bash

mkdir foo && cd foo
../.dotnet/dotnet new maui
../.dotnet/dotnet build -c Release -t:Run -f net7.0-android

Run the app a few times and make sure you get good launch times:

bash

$ adb logcat -d | grep Displayed
02-22 15:50:50.502  1802  1962 I ActivityTaskManager: Displayed com.companyname.foo/crc64808a40cc7e533249.MainActivity: +477ms
02-22 15:50:51.703  1802  1962 I ActivityTaskManager: Displayed com.companyname.foo/crc64808a40cc7e533249.MainActivity: +477ms
02-22 15:50:52.926  1802  1962 I ActivityTaskManager: Displayed com.companyname.foo/crc64808a40cc7e533249.MainActivity: +477ms

You can also use profile-android.ps1 in this repo, or profile.ps1.

Troubleshooting

If the resulting *.aotprofile.txt file is empty, review the .binlog file to see if there is a message like:

log

Task Exec 85ms
CommandLineArguments = "D:\.nuget\packages\mono.aotprofiler.android\9.0.0-preview1\tools\aprofutil"  -s -v -p 9999 -o "custom.aprof"
Reading from '127.0.0.1:9999'...
Read 19 bytes...
Read total 19 bytes...
Summary:
	Modules:          0
	Types:            0
	Methods:          0
Going to write the profile to 'custom.aprof'

Mono will print out more information to adb logcat if you set:

bash

adb shell setprop debug.mono.log default,assembly,mono_log_level=debug,mono_log_mask=all

Be sure to comment out the line in src\ProfiledAot\src\Directory.Build.targets that sets debug.mono.log to empty.

A working example of Mono's logging would say:

log

05-21 11:38:30.032 28555 28555 W monodroid: Initializing profiler with options: aot:port=9999,output=/data/user/0/com.companyname.maui/files/.__override__/arm64-v8a/profile.aotprofile
05-21 11:38:30.032 28555 28555 I monodroid-assembly: Trying to load shared library '/data/app/~~aLsIB6f0cwe4kpqTjGW6KA==/com.companyname.maui-8LChNbDvTnxGHnFnUt1vBw==/lib/arm64/libmono-profiler-aot.so'
05-21 11:38:30.033 28555 28555 W monodroid: Looking for profiler init symbol 'mono_profiler_init_aot'? 0x7826470468
...
05-21 11:38:35.531 28555 28586 I mono-prof: AOT profiler data written to 'socket'
05-21 11:38:35.534 28555 28586 E mono-prof: aot profiler data saved to the socket

Which could fail when loading the libmono-profiler-aot.so library, finding the mono_profiler_init_aot symbol, or just not return any data...

To fix this, you will need a new build of libmono-profiler-aot.so. We usually have to ship a new version of Mono.Profiler.Android with each major .NET version.

See some past examples at:

Notes about NuGet caches

To get a clear picture of before & after, you can copy over top of the previous profile with a command such as:

powershell

cp -Verbose src\Controls\src\Build.Tasks\nuget\buildTransitive\netstandard2.0\*.aotprofile ~\.nuget\packages\microsoft.maui.controls.build.tasks\9.0.100-preview.2-dev\buildTransitive\netstandard2.0\

Note that sometimes stale builds of MAUI can exist in your %NUGET_PACKAGES% directory, sometimes I even run a command to manually clear it completely of all *-dev directories:

powershell

rm -r ~\.nuget\packages\*\*-dev\

How to verify specific methods are AOT'd

To verify what methods are AOT'd, clear the log and enable AOT logging:

bash

adb logcat -c
adb shell setprop debug.mono.log default,timing=bare,assembly,mono_log_level=debug,mono_log_mask=aot

Restart the app, and you should be able to see messages like:

bash

$ adb logcat -d | grep AOT
02-23 09:03:46.327 10401 10401 D Mono    : AOT: FOUND method Microsoft.AspNetCore.Components.WebView.Maui.BlazorWebView:.ctor () [0x6f9efd0150 - 0x6f9efd0340 0x6f9efd260c]

Look for any suspicious AOT NOT FOUND messages.

Note that it is expected that some methods will say (wrapper):

bash

02-23 09:03:46.327 10401 10401 D Mono    : AOT NOT FOUND: (wrapper runtime-invoke) object:runtime_invoke_void (object,intptr,intptr,intptr).
02-23 09:03:46.334 10401 10401 D Mono    : AOT NOT FOUND: (wrapper managed-to-native) System.Diagnostics.Debugger:IsAttached_internal ().
02-23 09:03:46.367 10401 10401 D Mono    : AOT NOT FOUND: (wrapper native-to-managed) Android.Runtime.JNINativeWrapper:Wrap_JniMarshal_PPL_V (intptr,intptr,intptr).