[.NET] Build time is slower

[rolfbjarne]

Build time is significantly slower with .NET 6 than with Xamarin.iOS.

• Checkout and build the dotnet-size-comparison-helloworld branch from my fork.
• Execute:

cd tests/dotnet
git clean -xfdq
make compare

Then check the bin logs in the tests/dotnet directory.

Xamarin.iOS takes 11s to build:

$ msbuild /v:diag build-oldnet.binlog | tail -n 15
       62 ms  ResolveAssemblyReference                   1 calls
       69 ms  DetectSigningIdentity                      1 calls
      103 ms  DetectSdkLocations                         1 calls
      119 ms  SymbolStrip                                1 calls
      126 ms  SpotlightIndexer                           1 calls
      186 ms  Codesign                                   2 calls
      653 ms  DSymUtil                                   1 calls
      772 ms  Csc                                        1 calls
     8388 ms  MTouch                                     1 calls

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:11.24

.NET 6 takes 18s to build:

$ msbuild /v:diag build-dotnet.binlog | tail -n 15
      200 ms  MSBuild                                    7 calls
      296 ms  LinkNativeCode                             1 calls
      393 ms  GenerateDepsFile                           2 calls
      501 ms  Codesign                                   2 calls
      917 ms  Csc                                        1 calls
     1185 ms  AOTCompile                                 1 calls
     1222 ms  CopyRefAssembly                            1 calls
     3276 ms  CompileNativeCode                          2 calls
     8576 ms  ILLink                                     1 calls

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:18.55

The ILLink task significantly longer than the MTouch task used to take (which also includes AOT compilation and native code compilation).

[rolfbjarne]

CC @marek-safar

[spouliot]

P2 numbers. They look closer, between them [1], than the original numbers.

[1] this was done on a different (and slower) computer than the original post.

msbuild /v:diag build-oldnet.binlog | tail -n 15
      129 ms  SymbolStrip                                1 calls
      222 ms  ResolveAssemblyReference                   1 calls
      232 ms  SpotlightIndexer                           1 calls
      453 ms  DetectSdkLocations                         1 calls
      723 ms  DetectSigningIdentity                      1 calls
      881 ms  Codesign                                   2 calls
     1625 ms  DSymUtil                                   1 calls
     1745 ms  Csc                                        1 calls
    11812 ms  MTouch                                     1 calls

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:18.99

/Users/poupou/git/master/xamarin-macios/builds/downloads/dotnet-sdk-6.0.100-preview.2.21158.2-osx-x64/dotnet /Users/poupou/git/master/xamarin-macios/builds/downloads/dotnet-sdk-6.0.100-preview.2.21158.2-osx-x64/sdk/6.0.100-preview.2.21158.2/MSBuild.dll /v:diag build-dotnet.binlog | tail -n 15
      339 ms  LinkNativeCode                             1 calls
      341 ms  UnpackLibraryResources                     1 calls
      478 ms  GenerateDepsFile                           2 calls
      555 ms  DetectSigningIdentity                      1 calls
     1104 ms  AOTCompile                                 1 calls
     1408 ms  Csc                                        1 calls
     2833 ms  CompileNativeCode                          2 calls
     5142 ms  Codesign                                   2 calls
     5391 ms  ILLink                                     1 calls

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:21.39

[filipnavara]

The difference in Codesign is quite striking. Any explanation for it? (or .binlogs to analyze)

[spouliot]

@filipnavara I missed it (looked only at how MTouchTask is now split out) and I'm not sure why in this case [1]. Let me find back the binlogs... (binlogs.zip attached)

note: It seems there was already a large diff in Codesign numbers in the original post.

[1] some Apple tools (like ibtool) spawn daemons that stays alive (for a while) so running two builds sequentially can skew numbers.