Check for Empty ASP.NET Benchmark Filters + Documentation (#3870)

* Check for Empty Filters

* Fixed up documentation

* Removed trailing spaces to fix md linting

Author: mrsharm

src/benchmarks/gc/GC.Infrastructure/GC.Infrastructure/Commands/ASPNetBenchmarks/AspNetBenchmarksCommand.cs

@@ -258,6 +258,11 @@ public static AspNetBenchmarkResults RunASPNetBenchmarks(ASPNetBenchmarksConfigu
                         }
                     }
                 }
+
+                if (benchmarkToNameCommandAsKvpList.Count == 0)
+                {
+                    throw new ArgumentException($"{nameof(AspNetBenchmarksCommand)}: No benchmark filters found. Please ensure you have added the wildcard character to do the regex matching. Benchmark Filter: {configuration.benchmark_settings.benchmarkFilters}");
+                }
             }
 
             // Else, add all the benchmarks.

src/benchmarks/gc/GC.Infrastructure/README.md

@@ -209,6 +209,19 @@ It's worth noting that if you have specified Linux based binaries in the corerun
    1. Remove the ``crank`` prefix from the command line.
    2. Remove the ``--application.aspNetCoreVersion``, ``--application.runtimeVersion`` and ``--application.sdkVersion`` command args from the command line that you paste in the CSV as the versions are set by the infrastructure itself.
 
+###### How To Filter Benchmarks
+
+You can filter benchmarks of interest from the entire set of benchmarks specified by the referenced `benchmarks_file` using a list of regex patterns such as the following in the `benchmark_settings` section:
+
+```yaml
+benchmark_settings:
+  benchmark_filters:
+  - Stage1Aot_Windows*
+  - PlainText*
+```
+
+If there is a match, these filters will run in the order specified in the yaml file.
+
 ## All Commands
 
 The infrastructure can be run in modular manner. What this means is that you can invoke a particular command that runs some part of the infrastructure. A list of all the commands can be found here: