[Perf] Windows/x64: 1 Regression on 1/18/2023 1:01:18 AM

[performanceautofiler]

Run Information

Architecture	x64
OS	Windows 10.0.18362
Baseline	2e77a42d4563246f2362a498ca5906fdbd9274db
Compare	19fc478d67c2fc55e62b50676935f903a77f5a4d
Diff	Diff

Regressions in System.Text.Perf_Utf8Encoding

Benchmark	Baseline	Test	Test/Base	Test Quality	Edge Detector	Baseline IR	Compare IR	IR Ratio	Baseline ETL	Compare ETL
GetBytes - Duration of single invocation	127.23 μs	144.95 μs	1.14	0.02	False	1436061.9469026548	1488636.3636363635	1.0366101315107632	Trace	Trace

Test Report

Repro

git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f net8.0 --filter 'System.Text.Perf_Utf8Encoding*'

Payloads

Baseline
Compare

Histogram

System.Text.Perf_Utf8Encoding.GetBytes(Input: Chinese)

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 144.952449845679 > 133.54047838618894.
IsChangePoint: Marked as a change because one of 12/21/2022 9:23:17 AM, 1/17/2023 8:36:05 PM, 1/24/2023 6:33:57 AM falls between 1/15/2023 4:08:29 PM and 1/24/2023 6:33:57 AM.
IsRegressionStdDev: Marked as regression because -35.687283578257905 (T) = (0 -147617.61720326805) / Math.Sqrt((5647909.848760539 / (30)) + (2989695.2155531375 / (38))) is less than -1.9965644189515832 = MathNet.Numerics.Distributions.StudentT.InvCDF(0, 1, (30) + (38) - 2, .025) and -0.14273389516406024 = (129179.34597719695 - 147617.61720326805) / 129179.34597719695 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.

```### Baseline Jit Disasm

```assembly
; System.Text.Perf_Utf8Encoding.GetBytes()
       mov       rdx,rcx
       mov       rcx,[rdx+28]
       mov       rdx,[rdx+18]
       mov       rax,[rcx]
       mov       rax,[rax+58]
       jmp       qword ptr [rax+10]
; Total bytes of code 22

Compare Jit Disasm

; System.Text.Perf_Utf8Encoding.GetBytes()
       mov       rdx,rcx
       mov       rcx,[rdx+28]
       mov       rdx,[rdx+18]
       mov       rax,[rcx]
       mov       rax,[rax+58]
       jmp       qword ptr [rax+10]
; Total bytes of code 22

Docs

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

[EgorBo]

ping @adamsitnik it seems that the recent regression is from dotnet/runtime#80709 but the previous improvement is dotnet/runtime#75012

[adamsitnik]

@EgorBo in such case my only guess is code alignment (in dotnet/runtime#80709 I've added a new layer of abstraction which introduced regressions for small inputs and in dotnet/runtime#75012 I've removed it which solved these regressions)