[Perf -29%] PerfLabTests.CastingPerf (2)

[DrewScoggins]

Run Information

Architecture	x64
OS	Windows 10.0.18362
Changes	diff

Regressions in PerfLabTests.CastingPerf

Benchmark	Baseline	Test	Test/Base	Modality	Baseline Outlier
CheckObjIsInterfaceNo	218.29 μs	280.64 μs	1.29		False
CheckIsInstAnyIsInterfaceNo	218.29 μs	280.65 μs	1.29		False

Historical Data in Reporting System

Repro

git clone https://github.com/dotnet/performance.git
py .\performance\scripts\benchmarks_ci.py -f netcoreapp5.0 --filter 'PerfLabTests.CastingPerf*';

Histogram

PerfLabTests.CastingPerf.CheckObjIsInterfaceNo

[217888.775 ; 232960.149) | @@@@@@@@@@@@
[232960.149 ; 252981.511) | @@@@@@@@@@@@@@@@@@@@@@@@@@@@
[252981.511 ; 270375.304) | 
[270375.304 ; 285446.677) | @@@@@@@@@@@@@@@@@@@

PerfLabTests.CastingPerf.CheckIsInstAnyIsInterfaceNo

[209794.928 ; 226755.346) | @@@@@@@@@@@@@
[226755.346 ; 237218.013) | 
[237218.013 ; 254170.131) | @@@@@@@@@@@@@@@@@@@@@@@@@
[254170.131 ; 269951.518) | 
[269951.518 ; 286903.637) | @@@@@@@@@@@@@@@@@@@@
[286903.637 ; 303354.976) | 
[303354.976 ; 320307.095) | @

Docs

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

[DrewScoggins]

@adamsitnik @VSadov

[VSadov]

Could be the cost of tiered compiler indirection showing up on a fast cast. Native implementation did not have that expense.

The cost of tiering indirection could be easily avoided by opting out the casting helper from tiering. That would mean jitting it at start up time. We decided against that, since these are "fast" casts and generally not a perf concern.

I will take a look to be sure.