Investigate bimodal SpectralNorm_3

[adamsitnik]

The SpectralNorm_3 is a bimodal benchmark.

Example histograms from BenchmarkDotNet:

-------------------- Histogram --------------------
[0.786 ms ; 1.033 ms) | @
[1.033 ms ; 1.466 ms) | @@@@@@@@@@@@@@@@@@
[1.466 ms ; 1.807 ms) | @@@
[1.807 ms ; 2.240 ms) | @@@@@@@
[2.240 ms ; 2.875 ms) | @@@@@
[2.875 ms ; 3.288 ms) |
[3.288 ms ; 3.721 ms) | @@@@@@
---------------------------------------------------

-------------------- Histogram --------------------
[0.942 ms ; 1.237 ms) | @@@
[1.237 ms ; 1.614 ms) | @@@@@@@@@@
[1.614 ms ; 1.892 ms) | @
[1.892 ms ; 2.269 ms) | @@@@@@@
[2.269 ms ; 2.563 ms) | @@@
[2.563 ms ; 2.940 ms) | @@@@@@@@@
[2.940 ms ; 3.354 ms) | @@@@
[3.354 ms ; 3.731 ms) | @@@
---------------------------------------------------

Sample results from xunit-performance (please look at the Min and Max value):

DotNetBenchmark-spectralnorm-3.dll	Metric	Unit	Iterations	Average	STDEV.S	Min	Max
BenchmarksGame.SpectralNorm_3.RunBench	Duration	msec	6	1848.838	380.029	1517.790	2584.247

DotNetBenchmark-spectralnorm-3.dll	Metric	Unit	Iterations	Average	STDEV.S	Min	Max
BenchmarksGame.SpectralNorm_3.RunBench	Duration	msec	6	1928.860	173.474	1831.114	2272.792

We can get the diasm with BDN, but we need #40 to be implemented first to get profiles

[billwert]

Closing old issues like this as we have better techniques for finding these things now.