Burst Compile timing question

Unity Engine
1

It seems I get a hard 48ms every time I try to use the burst compiler.

Here is the data structure:

public struct TileGenerationData
    {
        public float3 TilePosition;
        public int X;
        public int Z;
        public int ChunkX;
        public int ChunkZ;

    }

Here is the Job:

[BurstCompile]
    public struct TileInitializationJob : IJobParallelFor
    {
        //Inputs
        public int ChunkSize;
        public int ChunkWidth;
        public int ChunkHeight;
        public float XSlice;
        public float ZSlice;

        //Outputs
        public NativeArray<TileGenerationData> result;

        public void Execute(int index)
        {
            TileGenerationData tData = result[index];

            //Calculation x, z given index
            tData.X = index / (ChunkSize * ChunkWidth);
            tData.Z = index % (ChunkSize * ChunkHeight);

            //Calculate Chunk indexes
            tData.ChunkX = tData.X / ChunkSize;
            tData.ChunkZ = tData.Z / ChunkSize;


            tData.TilePosition.x = (((tData.X + tData.Z * 0.5f - tData.Z / 2) * XSlice) - (XSlice * ChunkSize * tData.ChunkX)) + XSlice / 2;  //Add HexMetrics.XSlice/2 to center the hex
            tData.TilePosition.y = 0f;
            tData.TilePosition.z = ((tData.Z * ZSlice) - (ZSlice * ChunkSize * tData.ChunkZ)) + ZSlice / 1.5f;  //Add HexMetrics.ZSlice/1.5f to center the hex

            result[index] = tData;

        }
    }

Here is the usage:

//Initialize Creation Job
        TileInitializationJob createJob = new TileInitializationJob();
        createJob.ChunkSize = WorldMetrics.ChunkSize;
        createJob.ChunkWidth = WorldMetrics.WorldChunkWidth;
        createJob.ChunkHeight = WorldMetrics.WorldChunkHeight;
        createJob.XSlice = HexMetrics.XSlice;
        createJob.ZSlice = HexMetrics.ZSlice;
        createJob.result = _tilePositionData;

        JobHandle createJobHandle = createJob.Schedule(_tilePositionData.Length, createJob.ChunkSize);
        createJobHandle.Complete();

The timing I get from the burst compiler is as follows:
Burst timings (total: 48.8ms)

UpdateAssemblyCacheDirtyState: 1.1ms
FetchFromAssemblyCache: 0.0ms
ILCreateModule: 46.0ms
ILTransform: 0.0ms
ILAnalyzer: 0.0ms
ILHash: 0.9ms
IL2Module: 0.0ms
TargetModule: 0.1ms
StaticModule: 0.0ms
OptimizeModule: 0.0ms
CleanupModule: 0.0ms
PrintModule: 0.0ms
PrintModule: 0.0ms
VerifyModule: 0.0ms
AsmDump: 0.0ms
ILDump: 0.0ms
Initialize: 0.2ms
CompileModule: 0.0ms
LoadModuleFromCache: 0.0ms
SaveModuleToCache: 0.0ms
ExternalFunctions: 0.0ms

Total: 48.8ms

While compiling job: System.Void Unity.Jobs.IJobParallelForExtensions/ParallelForJobStruct`1<MainThread/TileInitializationJob>::Execute(T&,System.IntPtr,System.IntPtr,Unity.Jobs.LowLevel.Unsafe.JobRanges&,System.Int32)

Any help would be appreciated. Thanks!

2

I think I understand what is happening. This is only meant to be a one time job driven by a button click. I was using [BurstCompile(CompileSynchronously = true)] which will block the code to do its compilation. It seems the compilation will take ~50ms. I never run this again to see what the gain is after compilation so my profiler sees the roughly 50ms. For these one shots maybe I need to call the job with some dummy data outside of my loop so i know its compiled.

3

Right - that cost is only in the editor (when you build a player we’ll compile the thing during the player build for you).

If you want to profile some code you’ll want to spoof the job you have Burst compiled once before you begin timing so that we can identify and compile the code for you.

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