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IJobParallelForTransform, 15000 transforms, executed on single job thread, any hints?

Discussion in 'Data Oriented Technology Stack' started by jakub-gemrot, Jun 25, 2018.

  1. jakub-gemrot

    jakub-gemrot

    Joined:
    Nov 1, 2014
    Posts:
    10
    Hi!

    I'm playing with Job System, implemented simple scenario where cubes are falling down and being respawned once they hit a certain Y level. I have two jobs, the second dependent on the first. They both are referencing the same native array for transforms. It runs without errors/warnings but the job is never split among job threads.

    Job's code:
    Code (CSharp):
    1. namespace Ships.JobSystem
    2. {
    3.     [BurstCompile]
    4.     public struct MoveJob : IJobParallelForTransform
    5.     {      
    6.         public float speed;
    7.         public float deltaTime;
    8.  
    9.         public void Execute(int index, TransformAccess transform)
    10.         {
    11.             Vector3 position = transform.position;
    12.  
    13.             position = position + new Vector3(0, speed, 0) * deltaTime;
    14.  
    15.             transform.position = position;
    16.         }
    17.     }
    18. }

    Profiler as the proof (development build, not taken from the editor):
    Unity-JobSystem-Question.png


    Stats window:
    Unity-JobSystem-Question.2.png

    I'm running

    Version 2018.2.0b8 (fed204371f5a)
    Wed, 30 May 2018 15:35:38 GMT
    Branch: 2018.2/staging

    My project manifest:

    Code (CSharp):
    1. {
    2.     "dependencies": {
    3.         "com.unity.modules.ui": "1.0.0",
    4.         "com.unity.modules.tilemap": "1.0.0",
    5.         "com.unity.modules.physics2d": "1.0.0",
    6.         "com.unity.modules.assetbundle": "1.0.0",
    7.         "com.unity.modules.unitywebrequestassetbundle": "1.0.0",
    8.         "com.unity.modules.unityanalytics": "1.0.0",
    9.         "com.unity.modules.umbra": "1.0.0",
    10.         "com.unity.analytics": "2.0.16",
    11.         "com.unity.modules.vehicles": "1.0.0",
    12.         "com.unity.ads": "2.0.8",
    13.         "com.unity.modules.imageconversion": "1.0.0",
    14.         "com.unity.modules.director": "1.0.0",
    15.         "com.unity.modules.video": "1.0.0",
    16.         "com.unity.modules.audio": "1.0.0",
    17.         "com.unity.modules.unitywebrequest": "1.0.0",
    18.         "com.unity.textmeshpro": "1.2.1",
    19.         "com.unity.modules.ai": "1.0.0",
    20.         "com.unity.modules.unitywebrequestwww": "1.0.0",
    21.         "com.unity.purchasing": "2.0.1",
    22.         "com.unity.modules.particlesystem": "1.0.0",
    23.         "com.unity.standardevents": "1.0.13",
    24.         "com.unity.modules.imgui": "1.0.0",
    25.         "com.unity.modules.physics": "1.0.0",
    26.         "com.unity.modules.screencapture": "1.0.0",
    27.         "com.unity.modules.xr": "1.0.0",
    28.         "com.unity.modules.terrain": "1.0.0",
    29.         "com.unity.modules.unitywebrequestaudio": "1.0.0",
    30.         "com.unity.modules.jsonserialize": "1.0.0",
    31.         "com.unity.modules.terrainphysics": "1.0.0",
    32.         "com.unity.entities": "0.0.12-preview.6",
    33.         "com.unity.modules.animation": "1.0.0",
    34.         "com.unity.package-manager-ui": "2.0.0-preview.3",
    35.         "com.unity.modules.cloth": "1.0.0",
    36.         "com.unity.modules.uielements": "1.0.0",
    37.         "com.unity.modules.vr": "1.0.0",
    38.         "com.unity.modules.unitywebrequesttexture": "1.0.0",
    39.         "com.unity.modules.wind": "1.0.0",
    40.         "com.unity.incrementalcompiler": "0.0.42-preview.1"
    41.     },
    42.     "registry": "https://packages.unity.com",
    43.     "testables": [
    44.         "com.unity.collections",
    45.         "com.unity.entities",
    46.         "com.unity.jobs"
    47.     ]
    48. }
    Any suggestions what I might have missed to make my job be split among threads?

    Thank you!
    Jakub
     
    nishikinohojo likes this.
  2. jakub-gemrot

    jakub-gemrot

    Joined:
    Nov 1, 2014
    Posts:
    10
    Can it be that IJobParallelForTransform does not have an extension for setting the grouping?

    I have to schedule it like this:
    Code (CSharp):
    1. shipTransforms.moveJobHandle = moveJob.Schedule(shipTransforms.shipsAccess);
    While the code within ShipMoveJob is small, it still takes 2ms at single thread so by using 7 threads it can get down to 0,28ms...

    Jakub
     
  3. M_R

    M_R

    Joined:
    Apr 15, 2015
    Posts:
    547
    IJobParallelForTransform only splits the roots. if all your transforms have the same parent, they will execute in the same thread.

    try removing the parents for your cubes if you have any (or grouping them under different roots, at least >= the number of CPU threads)
     
  4. jakub-gemrot

    jakub-gemrot

    Joined:
    Nov 1, 2014
    Posts:
    10
    M_R is correct, I've split my objects among different parents and it works like a charm.
     
    PrimalCoder and OmegaNemesis28 like this.
  5. hippocoder

    hippocoder

    Digital Ape Moderator

    Joined:
    Apr 11, 2010
    Posts:
    26,890
    Unity needs a concept of a static parent or decorative parent so we can still keep things organised.
     
    tavovallejo, Sarkahn, koirat and 4 others like this.
  6. Nyanpas

    Nyanpas

    Joined:
    Dec 29, 2016
    Posts:
    353
    Is not ECS supposed to solve these things?
     
  7. Lurking-Ninja

    Lurking-Ninja

    Joined:
    Jan 20, 2015
    Posts:
    5,597
    No, ECS has nothing to do whether or not Unity has the concept of "decorative parent" in the Hierarchy window.
     
    Nyanpas likes this.
  8. Nyanpas

    Nyanpas

    Joined:
    Dec 29, 2016
    Posts:
    353
    Necrobump deluxe but I was thinking of the GameObject-conversion, anyhow problem solved.:oops:

    [edit] Just noticed that the job specified by OP is also not vectorized.
     
    Last edited: Aug 17, 2020
    hippocoder likes this.
  9. MagicianArtemka

    MagicianArtemka

    Joined:
    Jan 15, 2019
    Posts:
    23
    Hi. Can you provide an example of how OP's code can be vectorized? The code is simple and I cannot find a way to optimize it even more. I want to write better code for my projects - that's the reason why I'm asking ;)

    Also, I will be really appreciated it if you can provide here a few links to information about "vectorized code and how to write it". I think you are more experienced in DOTS than I'm, so you can know good books or articles about the vectorized code.
     
  10. Nyanpas

    Nyanpas

    Joined:
    Dec 29, 2016
    Posts:
    353
    Sorry, I cannot help. I am not an expert on the subject, I just read what the burst-inspector tells me...
     
    MagicianArtemka likes this.
  11. DreamingImLatios

    DreamingImLatios

    Joined:
    Jun 3, 2017
    Posts:
    2,096
    I'm one of the handful of people on these forums that could help you out.

    However, keep in mind that you should only try to vectorize code that is measurably expensive. Otherwise it is a waste of time, because you can only get up to 4x speedup (8x if using AVX) unless you also fix other things related to aliasing, branching, and caching. Anyways, if you have a particular job that you measured to be too expensive and you would like to performance golf, either start a new thread and tag me or PM me directly if you don't want to share it publicly.
     
    MagicianArtemka likes this.
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