Performance regression come again on dotnet 9

[kingsznhone]

Description

#95954
With temporary resolution in this issue . I add this segment to fix dotnet 8 performance regression. It makes performance back to 90% of dotnet 7
https://github.com/kingsznhone/VSOP2013.NET/blob/8a9e03fd734d9c29de788877724e32022b042d21/VSOP2013.NET/Calculator.cs#L151

Few days ago. I try dotnet 9 to run perf test. Same situation occor as before.

Ethier I apply that fix or not. Performance still very bad.

This line cause performance heavily drop as before.
(su, cu) = Math.SinCos(u);

Data

``

BenchmarkDotNet v0.13.11, Windows 11 (10.0.22631.4602/23H2/2023Update/SunValley3)
12th Gen Intel Core i9-12950HX, 1 CPU, 16 logical and 16 physical cores
.NET SDK 9.0.101
[Host] : .NET 8.0.11 (8.0.1124.51707), X64 RyuJIT AVX2 [AttachedDebugger]
.NET 8.0 : .NET 8.0.11 (8.0.1124.51707), X64 RyuJIT AVX2
.NET 9.0 : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX2

| Method  | Job      | Runtime  | Mean        | Error     | StdDev    | Ratio | Allocated | Alloc Ratio |
|-------- |--------- |--------- |------------:|----------:|----------:|------:|----------:|------------:|
| Compute | .NET 8.0 | .NET 8.0 |    739.2 μs |   8.05 μs |   7.14 μs |  1.00 |   2.91 KB |        1.00 |
|         |          |          |             |           |           |       |           |             |
| Compute | .NET 9.0 | .NET 9.0 | 29,018.1 μs | 183.88 μs | 172.00 μs |  1.00 |   2.92 KB |        1.00 |

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[tannergooding]

I do measure a regression, but nowhere near what you're seeing (on Intel or AMD)

This is due to an MSVC correctness bug that exists in native: https://developercommunity.visualstudio.com/t/MSVCs-sincos-implementation-is-incorrec/10582378 and thus .NET 9 was fixed to no longer use the /fp:fast implementation and invokes the /fp:precise one instead. .NET 8 retains the buggy behavior and will return an incorrect Cos result for some large inputs.

The exact performance is a bit dependent on the input, but it should be pessimizing to approximately the same performance as if you invoked Sin and Cos independently, which is what I'm getting locally.

Intel

BenchmarkDotNet v0.13.11, Windows 11 (10.0.26100.2605)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 16 logical and 8 physical cores
.NET SDK 9.0.100
  [Host]   : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  .NET 8.0 : .NET 8.0.10 (8.0.1024.46610), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  .NET 9.0 : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Job	Runtime	Mean	Error	StdDev	Ratio	Code Size	Allocated	Alloc Ratio
Compute	.NET 8.0	.NET 8.0	1.397 ms	0.0119 ms	0.0117 ms	1.00	314 B	2.9 KB	1.00
Compute	.NET 9.0	.NET 9.0	2.281 ms	0.0068 ms	0.0064 ms	1.00	314 B	2.9 KB	1.00

AMD

BenchmarkDotNet v0.13.11, Windows 11 (10.0.26100.2605)
AMD Ryzen 9 7950X, 1 CPU, 32 logical and 16 physical cores
.NET SDK 9.0.200-preview.0.24575.35
  [Host]   : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  .NET 8.0 : .NET 8.0.11 (8.0.1124.51707), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  .NET 9.0 : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Job	Runtime	Mean	Error	StdDev	Ratio	Code Size	Allocated	Alloc Ratio
Compute	.NET 8.0	.NET 8.0	714.2 us	2.00 us	1.56 us	1.00	314 B	2.92 KB	1.00
Compute	.NET 9.0	.NET 9.0	1,314.8 us	5.29 us	4.69 us	1.00	314 B	2.9 KB	1.00

[kingsznhone]

I do measure a regression, but nowhere near what you're seeing (on Intel or AMD)

This is due to an MSVC correctness bug that exists in native: https://developercommunity.visualstudio.com/t/MSVCs-sincos-implementation-is-incorrec/10582378 and thus .NET 9 was fixed to no longer use the /fp:fast implementation and invokes the /fp:precise one instead. .NET 8 retains the buggy behavior and will return an incorrect Cos result for some large inputs.

The exact performance is a bit dependent on the input, but it should be pessimizing to approximately the same performance as if you invoked Sin and Cos independently, which is what I'm getting locally.

Intel

BenchmarkDotNet v0.13.11, Windows 11 (10.0.26100.2605)
Intel Xeon Platinum 8370C CPU 2.80GHz, 1 CPU, 16 logical and 8 physical cores
.NET SDK 9.0.100
  [Host]   : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  .NET 8.0 : .NET 8.0.10 (8.0.1024.46610), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  .NET 9.0 : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Job	Runtime	Mean	Error	StdDev	Ratio	Code Size	Allocated	Alloc Ratio
Compute	.NET 8.0	.NET 8.0	1.397 ms	0.0119 ms	0.0117 ms	1.00	314 B	2.9 KB	1.00
Compute	.NET 9.0	.NET 9.0	2.281 ms	0.0068 ms	0.0064 ms	1.00	314 B	2.9 KB	1.00

AMD

BenchmarkDotNet v0.13.11, Windows 11 (10.0.26100.2605)
AMD Ryzen 9 7950X, 1 CPU, 32 logical and 16 physical cores
.NET SDK 9.0.200-preview.0.24575.35
  [Host]   : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  .NET 8.0 : .NET 8.0.11 (8.0.1124.51707), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI
  .NET 9.0 : .NET 9.0.0 (9.0.24.52809), X64 RyuJIT AVX-512F+CD+BW+DQ+VL+VBMI

Method	Job	Runtime	Mean	Error	StdDev	Ratio	Code Size	Allocated	Alloc Ratio
Compute	.NET 8.0	.NET 8.0	714.2 us	2.00 us	1.56 us	1.00	314 B	2.92 KB	1.00
Compute	.NET 9.0	.NET 9.0	1,314.8 us	5.29 us	4.69 us	1.00	314 B	2.9 KB	1.00

I notice that your platform have avx512 support, but my laptop only got avx2. Or it might be a exclusive bug of 12/13/14th gen core CPU,lol

As you say, I think I should call sin & cos seperately in the future, to aviod strange behaviour. thanks

[jeffhandley]

Assigned to @PranavSenthilnathan for triage.