[wasm][bench] Limit initial samples (#86953)

* [wasm][bench] Limit initial samples

Try to limit initial samples measurement to 1 second.

Currently some of string measurements with hybrid globalization turned on
can take hundreds of seconds. This makes the browser stop the benchmark
and the measurement job times out.

This should limit the initial samples to take cca 1 second or take just
one initial sample if it takes more time.

Also increase the initial samples for string comparison, where it was on
the edge and the times were flipping between cca 5 and 10 seconds.

* Do GC collect only when doing initial samples

Author: radekdoulik

src/mono/sample/wasm/browser-bench/BenchTask.cs

@@ -59,15 +59,16 @@ public virtual void RunStep() { }
 
         public virtual bool HasRunStepAsync => false;
 
-        protected virtual int CalculateSteps(int milliseconds, TimeSpan initTs)
+        protected virtual int CalculateSteps(int milliseconds, TimeSpan initTs, int initialSamples)
         {
-            return (int)(milliseconds * InitialSamples / Math.Max(1.0, initTs.TotalMilliseconds));
+            return (int)(milliseconds * initialSamples / Math.Max(1.0, initTs.TotalMilliseconds));
         }
 
         public async Task<Result> RunBatch(BenchTask task, int milliseconds)
         {
             DateTime start = DateTime.Now;
             DateTime end;
+            int initialSamples = InitialSamples;
             try
             {
                 // run one to eliminate possible startup overhead and do GC collection
@@ -79,15 +80,35 @@ public async Task<Result> RunBatch(BenchTask task, int milliseconds)
                 GC.Collect();
 
                 start = DateTime.Now;
-                for (currentStep = 0; currentStep < InitialSamples; currentStep++)
-                    if (HasRunStepAsync)
-                        await RunStepAsync();
-                    else
-                        RunStep();
+                if (HasRunStepAsync)
+                    await RunStepAsync();
+                else
+                    RunStep();
                 end = DateTime.Now;
 
+                // try to limit initial samples to 1s
+                var oneTs = end - start;
+                var maxInitMs = 1000;
+                if (oneTs.TotalMilliseconds > 0 && oneTs.TotalMilliseconds*InitialSamples > maxInitMs)
+                    initialSamples = (int)(maxInitMs/oneTs.TotalMilliseconds);
+
+                if (initialSamples > 1) {
+                    GC.Collect();
+
+                    start = DateTime.Now;
+                    for (currentStep = 0; currentStep < initialSamples; currentStep++)
+                        if (HasRunStepAsync)
+                            await RunStepAsync();
+                        else
+                            RunStep();
+                    end = DateTime.Now;
+                } else {
+                    // we already have the 1st measurement
+                    initialSamples = 1;
+                }
+
                 var initTs = end - start;
-                int steps = CalculateSteps(milliseconds, initTs);
+                int steps = CalculateSteps(milliseconds, initTs, initialSamples);
 
                 start = DateTime.Now;
                 for (currentStep = 0; currentStep < steps; currentStep++)
@@ -101,14 +122,14 @@ public async Task<Result> RunBatch(BenchTask task, int milliseconds)
 
                 var ts = end - start;
 
-                return new Result { span = ts + initTs, steps = steps + InitialSamples, taskName = task.Name, measurementName = Name };
+                return new Result { span = ts + initTs, steps = steps + initialSamples, taskName = task.Name, measurementName = Name };
             }
             catch (Exception ex)
             {
                 end = DateTime.Now;
                 var ts = end - start;
                 Console.WriteLine(ex);
-                return new Result { span = ts, steps = currentStep + InitialSamples, taskName = task.Name, measurementName = Name + " " + ex.Message };
+                return new Result { span = ts, steps = currentStep + initialSamples, taskName = task.Name, measurementName = Name + " " + ex.Message };
             }
         }
     }

src/mono/sample/wasm/browser-bench/String.cs

@@ -139,6 +139,8 @@ public class TextInfoToTitleCase : TextInfoMeasurement
 
         public abstract class StringsCompare : StringMeasurement
         {
+            public override int InitialSamples => 100;
+
             protected string strAsciiSuffix;
             protected string strAsciiPrefix;
             protected string needleSameAsStrEnd;

src/mono/sample/wasm/browser-bench/WebSocket.cs

@@ -88,7 +88,7 @@ public class PartialSend_1BMeasurement : WebSocketMeasurement
             public override int InitialSamples => 1000;
             ArraySegment<byte> buffer = new ArraySegment<byte>(new byte[1]);
 
-            protected override int CalculateSteps(int milliseconds, TimeSpan initTs)
+            protected override int CalculateSteps(int milliseconds, TimeSpan initTs, int initialSamples)
             {
                 return 250_000;
             }
@@ -112,7 +112,7 @@ public PartialSend_64KBMeasurement()
                     buffer[i] = (byte)(i & 0xff);
                 }
             }
-            protected override int CalculateSteps(int milliseconds, TimeSpan initTs)
+            protected override int CalculateSteps(int milliseconds, TimeSpan initTs, int initialSamples)
             {
                 return 3000;
             }
@@ -137,7 +137,7 @@ public PartialSend_1MBMeasurement()
                     buffer[i] = (byte)(i & 0xff);
                 }
             }
-            protected override int CalculateSteps(int milliseconds, TimeSpan initTs)
+            protected override int CalculateSteps(int milliseconds, TimeSpan initTs, int initialSamples)
             {
                 return 100;
             }
@@ -154,9 +154,9 @@ public class PartialReceive_1BMeasurement : WebSocketReceiveMeasurement
         {
             ArraySegment<byte> buffer = new ArraySegment<byte>(new byte[1]);
 
-            protected override int CalculateSteps(int milliseconds, TimeSpan initTs)
+            protected override int CalculateSteps(int milliseconds, TimeSpan initTs, int initialSamples)
             {
-                return MaxLength - InitialSamples - 100;
+                return MaxLength - initialSamples - 100;
             }
 
             public override void RunStep()
@@ -177,7 +177,7 @@ public class PartialReceive_10KBMeasurement : WebSocketReceiveMeasurement
             public override int InitialSamples => 1;
             ArraySegment<byte> buffer = new ArraySegment<byte>(new byte[bufferSize]);
 
-            protected override int CalculateSteps(int milliseconds, TimeSpan initTs)
+            protected override int CalculateSteps(int milliseconds, TimeSpan initTs, int initialSamples)
             {
                 return 500;
             }
@@ -206,7 +206,7 @@ public class PartialReceive_100KBMeasurement : WebSocketReceiveMeasurement
             public override int InitialSamples => 1;
             ArraySegment<byte> buffer = new ArraySegment<byte>(new byte[bufferSize]);
 
-            protected override int CalculateSteps(int milliseconds, TimeSpan initTs)
+            protected override int CalculateSteps(int milliseconds, TimeSpan initTs, int initialSamples)
             {
                 return MaxMessages - 1;
             }