[Perf -493%] System.Linq.Tests.Perf_Enumerable.FirstWithPredicate_LastElementMatches

[adamsitnik]

I am now running an independent 3.1 vs 5.0 comparison and I've confirmed that it's actual regression introduced in 5.0.

The issue has been originally reported by a bot owned by @DrewScoggins in DrewScoggins/performance-2#860 Since I can't transfer issues from https://github.com/DrewScoggins/performance-2/ to https://github.com/dotnet/runtime I have simply copy-pasted its original content:

Run Information

Architecture	x64
OS	Windows 10.0.18362
Changes	diff

Regressions in System.Linq.Tests.Perf_Enumerable

Benchmark	Baseline	Test	Test/Base	Modality	Baseline Outlier
FirstWithPredicate_LastElementMatches	663.99 ns	3.93 μs	5.92	Bimodal	True

Historical Data in Reporting System

Repro

git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f netcoreapp5.0 --filter 'System.Linq.Tests.Perf_Enumerable.FirstWithPredicate_LastElementMatches'

Histogram

System.Linq.Tests.Perf_Enumerable.FirstWithPredicate_LastElementMatches(input: IOrderedEnumerable)

[ 574.083 ;  819.245) | @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
[ 819.245 ; 1064.407) | 
[1064.407 ; 1309.569) | 
[1309.569 ; 1554.731) | 
[1554.731 ; 1799.892) | 
[1799.892 ; 2045.054) | 
[2045.054 ; 2290.216) | 
[2290.216 ; 2535.378) | 
[2535.378 ; 2780.539) | 
[2780.539 ; 3025.701) | 
[3025.701 ; 3270.863) | 
[3270.863 ; 3516.025) | 
[3516.025 ; 3825.415) | 
[3825.415 ; 4101.643) | @@@@@@

Docs

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

[ghost]

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[adamsitnik]

System.Linq.Tests.Perf_Enumerable.FirstWithPredicate_LastElementMatches(input: IOrderedEnumerable)

Conclusion	Base	Diff	Base/Diff	Modality	Operating System	Bit	Processor Name	Base Runtime	Diff Runtime
Slower	972.74	8054.46	0.12		Windows 10.0.18363.1016	Arm	Microsoft SQ1 3.0 GHz	.NET Core 3.1.6	5.0.100-rc.1.20413.9
Slower	598.37	3519.26	0.17		Windows 10.0.18363.959	X64	Intel Xeon CPU E5-1650 v4 3.60GHz	.NET Core 3.1.6	5.0.100-rc.1.20404.3
Slower	610.20	3674.19	0.17		Windows 10.0.18363.959	X64	Intel Xeon CPU E5-1650 v4 3.60GHz	.NET Core 3.1.6	5.0.100-rc.1.20418.3
Slower	700.86	4238.85	0.17		Windows 10.0.19041.450	X64	Intel Core i7-5557U CPU 3.10GHz (Broadwell)	.NET Core 3.1.6	5.0.100-rc.1.20413.9
Slower	626.94	3928.55	0.16		ubuntu 18.04	X64	Intel Xeon CPU E5-1650 v4 3.60GHz	.NET Core 3.1.6	5.0.100-rc.1.20403.23
Slower	743.69	4727.58	0.16		macOS Mojave 10.14.5	X64	Intel Core i7-5557U CPU 3.10GHz (Broadwell)	.NET Core 3.1.6	5.0.100-rc.1.20404.2

[stephentoub]

Dup of #39032 (comment)