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[Perf] Windows/x64: Half and FrozenDictionary Regressions on 1/28/2025 11:31:49 PM +00:00 #112135

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[Perf] Windows/x64: Half and FrozenDictionary Regressions on 1/28/2025 11:31:49 PM +00:00#112135
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EgorBo
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arch-x64area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMIos-windowsruntime-coreclrspecific to the CoreCLR runtimetenet-performancePerformance related issuetenet-performance-benchmarksIssue from performance benchmark
Milestone
10.0.0

Description

@performanceautofiler
performanceautofiler
bot
opened on Feb 4, 2025

Run Information

Name Value
Architecture x64
OS Windows 10.0.22621
Queue TigerWindows
Baseline d20c35e05c16dd2ec9cddd4259738cc02228d425
Compare d9b75154ad360154b863ee01b72fbef94de261b0
Diff Diff
Configs CompilationMode:tiered, RunKind:micro

Regressions in System.Tests.Perf_Half

Benchmark Baseline Test Test/Base Test Quality Edge Detector Baseline IR Compare IR IR Ratio
1.01 ns 2.25 ns 2.24 0.04 False
1.01 ns 2.25 ns 2.24 0.04 False

graph
graph
Test Report

Repro

General Docs link: https://github.com/dotnet/performance/blob/main/docs/benchmarking-workflow-dotnet-runtime.md

git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Tests.Perf_Half*'
Details

System.Tests.Perf_Half.HalfToSingle(value: 12344)

ETL Files

Histogram

JIT Disasms

System.Tests.Perf_Half.HalfToSingle(value: NaN)

ETL Files

Histogram

JIT Disasms

Docs

Profiling workflow for dotnet/runtime repository
Benchmarking workflow for dotnet/runtime repository

Run Information

Name Value
Architecture x64
OS Windows 10.0.22621
Queue TigerWindows
Baseline d20c35e05c16dd2ec9cddd4259738cc02228d425
Compare d9b75154ad360154b863ee01b72fbef94de261b0
Diff Diff
Configs CompilationMode:tiered, RunKind:micro

Regressions in System.Collections.Perf_Frozen<Int16>

Benchmark Baseline Test Test/Base Test Quality Edge Detector Baseline IR Compare IR IR Ratio
50.64 ns 59.55 ns 1.18 0.01 False

graph
Test Report

Repro

General Docs link: https://github.com/dotnet/performance/blob/main/docs/benchmarking-workflow-dotnet-runtime.md

git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Collections.Perf_Frozen&lt;Int16&gt;*'
Details

System.Collections.Perf_Frozen<Int16>.ToFrozenDictionary(Count: 4)

ETL Files

Histogram

JIT Disasms

Docs

Profiling workflow for dotnet/runtime repository
Benchmarking workflow for dotnet/runtime repository

Activity

  1. performanceautofiler
    added
    arch-x64
    os-windows
    runtime-coreclrspecific to the CoreCLR runtime
    untriagedNew issue has not been triaged by the area owner
    on Feb 4, 2025

  2. LoopedBard3 commented on Feb 4, 2025

    @LoopedBard3
    LoopedBard3
    on Feb 4, 2025
    Member

    From range: 9b24fb6...21ab780, Half test regressions were caused by #111024 (FYI @EgorBo) and Frozen Dictionary Regression was caused by #111886 (FYI @stephentoub).

    Related Regressions:

  3. LoopedBard3
    changed the title [-][Perf] Windows/x64: 3 Regressions on 1/28/2025 11:31:49 PM +00:00[/-] [+][Perf] Windows/x64: Half and FrozenDictionary Regressions on 1/28/2025 11:31:49 PM +00:00[/+] on Feb 4, 2025
  4. LoopedBard3
    transferred this issue fromdotnet/perf-autofiling-issueson Feb 4, 2025
  5. ghost added
    needs-area-labelAn area label is needed to ensure this gets routed to the appropriate area owners
    on Feb 4, 2025
  6. LoopedBard3
    added
    tenet-performancePerformance related issue
    tenet-performance-benchmarksIssue from performance benchmark
    on Feb 4, 2025
  7. jeffschwMSFT
    added
    area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
    on Feb 6, 2025

  8. dotnet-policy-service commented on Feb 6, 2025

    @dotnet-policy-service
    dotnet-policy-serviceBot
    on Feb 6, 2025 – with Dotnet Policy Service
    Contributor

    Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
    See info in area-owners.md if you want to be subscribed.

  9. JulieLeeMSFT
    assigned
    EgorBo
    on Feb 6, 2025
  10. JulieLeeMSFT
    removed
    untriagedNew issue has not been triaged by the area owner
    on Feb 6, 2025
  11. JulieLeeMSFT
    added this to the 10.0.0 milestone on Feb 6, 2025

  12. xtqqczze commented on Feb 7, 2025

    @xtqqczze
    xtqqczze
    on Feb 7, 2025
    Contributor

    @tannergooding Is this beneficial? 2 bytes higher in code size, but 0.75 lower PerfScore.

    MihuBot/runtime-utils#854

     ; Assembly listing for method System.Half:op_Explicit(float):System.Half (FullOpts)
+       xor      ecx, ecx
+       mov      edx, -1
        vucomiss xmm0, xmm0
-       setp     cl
-       movzx    rcx, cl
-       dec      ecx
+       cmovnp   ecx, edx

    Related: #61761 (comment)

    Originally posted by @xtqqczze in #111024 (comment)

  13. stephentoub commented on Feb 8, 2025

    @stephentoub
    stephentoub
    on Feb 8, 2025
    Member

    The ToFrozenDictionary one is acceptable. #112298 will help a little, but this is a 9ns regression when constructing the FrozenDictionary, in order to improve the throughput of accessing it. That kind of tradeoff is the main reason this type exists: we're ok spending a bit more at construction in order to optimize throughput of reads.

  14. vcsjones
    removed
    needs-area-labelAn area label is needed to ensure this gets routed to the appropriate area owners
    on Feb 18, 2025

  15. EgorBo commented on Jul 16, 2025

    @EgorBo
    EgorBo
    on Jul 16, 2025
    Member

    Closing per Stephen comment. All Half-related regressions seem no longer relevant, e.g.

    Image
  16. EgorBo
    closed this as completedon Jul 16, 2025
  17. github-actions
    locked and limited conversation to collaborators on Aug 16, 2025
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