The frame times of my toy ray tracer increased from 24ms to 30ms #78127

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1. BTOdell

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   tenet-performancePerformance related issuePerformance related issue

   on Nov 9, 2022
3. ghost added

   untriagedNew issue has not been triaged by the area ownerNew issue has not been triaged by the area owner

   on Nov 9, 2022
4. AndyAyersMS commented on Nov 9, 2022

   

   AndyAyersMS

   on Nov 9, 2022

   Last edited by AndyAyersMS

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   This is a result of the new On-Stack Replacement feature (aka OSR) in .NET 7. You can disable this feature by adding the following lines to your csproj

     <PropertyGroup>
       <TieredCompilationQuickJitForLoops>false</TieredCompilationQuickJitForLoops>
     </PropertyGroup>

   When I do this, I see ~5% faster times for .NET 7.

   [edit: fixed the property name and value]

   FYI @dotnet/jit-contrib -- I have not yet drilled in to see where OSR is losing perf.

   👍React with 👍2Reacted by Bradley Odell and Avahe Kellenberger
5. AndyAyersMS

   added

   area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMICLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI

   and removed

   untriagedNew issue has not been triaged by the area ownerNew issue has not been triaged by the area owner

   on Nov 9, 2022
7. AndyAyersMS commented on Nov 9, 2022

   

   AndyAyersMS

   on Nov 9, 2022

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   Related: #67594.
8. AndyAyersMS commented on Nov 10, 2022

   

   AndyAyersMS

   on Nov 10, 2022

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   Profile of 20 seconds of the app on .NET 7 (with default behavior)

   I think perfview's attribution of Run as "ReadyToRun" is wrong, this is OSR code.

   

   Corresponding profile from .NET 6

   

   Looking at Run the inner loop codegen is actually fairly similar, except that the OSR method seems to have realized that Vec4.One is a constant -- but then it fails to hoist/CSE this constant and reloads it repeatedly. That might be the regression. It's possible hoisting is thrown off by lack of a preheader or something.
9. JulieLeeMSFT

   added this to the 8.0.0 milestone on Nov 10, 2022
10. JulieLeeMSFT

    assigned

    AndyAyersMS

    on Nov 10, 2022
11. danmoseley

    added

    regression-from-last-release

    on Nov 10, 2022
12. AndyAyersMS commented on Mar 31, 2023

    

    AndyAyersMS

    on Mar 31, 2023

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    This seems to be fixed with latest .NET 8 builds (will be available in Preview 4)

    ;; 7.0
    Framebuffer size: <800, 800>
    Rendered in: 138.3371ms
    Rendered in: 115.2097ms
    Rendered in: 60.8962ms
    Rendered in: 27.6196ms
    Rendered in: 27.1536ms
    Rendered in: 27.0591ms
    Rendered in: 27.4292ms
    Rendered in: 27.1339ms
    Rendered in: 27.1519ms
    
    ;; 8.0 current main
    Framebuffer size: <800, 800>
    Rendered in: 133.7311ms
    Rendered in: 108.3345ms
    Rendered in: 65.7654ms
    Rendered in: 24.2893ms
    Rendered in: 26.8595ms
    Rendered in: 24.5418ms
    Rendered in: 23.7889ms
    Rendered in: 24.2502ms
    Rendered in: 23.6659ms
    Rendered in: 23.9037ms
    Rendered in: 23.8969ms
    

    I' m going to close this. @BTOdell once Preview 4 is out give it a try and see if you see the same. If not, please re-open.
13. AndyAyersMS

    closed this as completedon Mar 31, 2023
14. ghost locked as resolved and limited conversation to collaborators on Apr 30, 2023