[Perf] Regressions in System.Memory.Span<Char>

[performanceautofiler]

Regressions in System.Memory.Span<Char>

Benchmark	Baseline	Test	Test/Base	Test Quality	Edge Detector	Baseline IR	Compare IR	IR Ratio	Baseline ETL	Compare ETL
LastIndexOfValue - Duration of single invocation	29.35 ns	33.23 ns	1.13	0.03	False

Test Report

Repro

git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f net6.0 --filter 'System.Memory.Span<Char>*'

Payloads

Baseline
Compare

Histogram

Edge Detector Info

Collection Data

System.Memory.Span<Char>.LastIndexOfValue(Size: 512)

Description of detection logic

IsRegressionChecked: Marked as regression because the three check build points were 0.05 greater than the baseline.
IsImprovementBase: Marked as not an improvement because the compare was not 5% less than the baseline, or the value was too small.
IsRegressionBase: Marked as regression because the compare was 5% greater than the baseline, and the value was not too small.
IsRegressionChecked: Marked as regression because the three check build points were 0.05 greater than the baseline.
IsRegressionWindowed: Marked as regression because 33.234352970999026 > 30.80907330059995.
IsChangePoint: Marked as a change because one of 7/2/2022 7:35:06 PM, 7/6/2022 3:55:24 AM, 8/17/2022 10:14:53 AM, 9/13/2022 2:36:07 PM, 9/22/2022 3:16:12 AM falls between 9/13/2022 2:36:07 PM and 9/22/2022 3:16:12 AM.
IsRegressionStdDev: Marked as regression because -15.831977795834955 (T) = (0 -31.808116157488204) / Math.Sqrt((0.011066090212876852 / (15)) + (0.9197330397655085 / (38))) is less than -2.007583770314729 = MathNet.Numerics.Distributions.StudentT.InvCDF(0, 1, (15) + (38) - 2, .025) and -0.08531215543829654 = (29.307804209234803 - 31.808116157488204) / 29.307804209234803 is less than -0.05.
IsImprovementBase: Marked as not an improvement because the compare was not 5% less than the baseline, or the value was too small.
IsChangeEdgeDetector: Marked not as a regression because Edge Detector said so.
IsChangeEdgeDetector: Marked not as a regression because Edge Detector said so.

Docs

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

[dotnet-issue-labeler]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[DrewScoggins]

Seems related to #75857

[ghost]

Tagging subscribers to this area: @dotnet/area-system-memory
See info in area-owners.md if you want to be subscribed.

Issue Details

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Regressions in System.Memory.Span<Char>

Benchmark	Baseline	Test	Test/Base	Test Quality	Edge Detector	Baseline IR	Compare IR	IR Ratio	Baseline ETL	Compare ETL
LastIndexOfValue - Duration of single invocation	29.35 ns	33.23 ns	1.13	0.03	False

Test Report

Repro

git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f net6.0 --filter 'System.Memory.Span<Char>*'

Payloads

Baseline
Compare

Histogram

Edge Detector Info

Collection Data

System.Memory.Span<Char>.LastIndexOfValue(Size: 512)

Description of detection logic

IsRegressionChecked: Marked as regression because the three check build points were 0.05 greater than the baseline.
IsImprovementBase: Marked as not an improvement because the compare was not 5% less than the baseline, or the value was too small.
IsRegressionBase: Marked as regression because the compare was 5% greater than the baseline, and the value was not too small.
IsRegressionChecked: Marked as regression because the three check build points were 0.05 greater than the baseline.
IsRegressionWindowed: Marked as regression because 33.234352970999026 > 30.80907330059995.
IsChangePoint: Marked as a change because one of 7/2/2022 7:35:06 PM, 7/6/2022 3:55:24 AM, 8/17/2022 10:14:53 AM, 9/13/2022 2:36:07 PM, 9/22/2022 3:16:12 AM falls between 9/13/2022 2:36:07 PM and 9/22/2022 3:16:12 AM.
IsRegressionStdDev: Marked as regression because -15.831977795834955 (T) = (0 -31.808116157488204) / Math.Sqrt((0.011066090212876852 / (15)) + (0.9197330397655085 / (38))) is less than -2.007583770314729 = MathNet.Numerics.Distributions.StudentT.InvCDF(0, 1, (15) + (38) - 2, .025) and -0.08531215543829654 = (29.307804209234803 - 31.808116157488204) / 29.307804209234803 is less than -0.05.
IsImprovementBase: Marked as not an improvement because the compare was not 5% less than the baseline, or the value was too small.
IsChangeEdgeDetector: Marked not as a regression because Edge Detector said so.
IsChangeEdgeDetector: Marked not as a regression because Edge Detector said so.

Docs

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

Author:	performanceautofiler[bot]
Assignees:	dakersnar
Labels:	arch-arm64, area-System.Memory, tenet-performance, tenet-performance-benchmarks, untriaged
Milestone:	-

[adamsitnik]

It went up, and down after a few days:

Since #75857 was a bug fix and we can't revert even if it caused a regression, I am going to close the issue.