[Perf] Display results with 4 significant figures

common/Perf/Azure.Test.Perf/NumberFormatter.cs

@@ -0,0 +1,41 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+
+namespace Azure.Test.Perf
+{
+    public static class NumberFormatter
+    {
+        // Formats a number with a minimum number of significant digits.
+        // Digits to the left of the decimal point are always significant.
+        // Examples:
+        // - Format(0, 4) -> "0.000"
+        // - Format(12345, 4) -> "12,345"
+        // - Format(1.2345, 4) -> "1.235"
+        // - Format(0.00012345, 4) -> "0.0001235"
+        public static string Format(double value, int minSignificantDigits, bool groupSeparator = true)
+        {
+            if (minSignificantDigits <= 0)
+            {
+                throw new ArgumentException("Must be greater than zero", nameof(minSignificantDigits));
+            }
+
+            // Special case since log(0) is undefined
+            if (value == 0)
+            {
+                return value.ToString($"F{minSignificantDigits - 1}");
+            }
+
+            double log = Math.Log10(Math.Abs(value));
+            int significantDigits = (int)Math.Max(Math.Ceiling(log), minSignificantDigits);
+
+            double divisor = Math.Pow(10, Math.Ceiling(log) - significantDigits);
+            double rounded = divisor * Math.Round(value / divisor, MidpointRounding.AwayFromZero);
+
+            int decimals = (int)Math.Max(0, significantDigits - Math.Floor(log) - 1);
+
+            return rounded.ToString(groupSeparator ? $"N{decimals}" : $"F{decimals}");
+        }
+    }
+}

common/Perf/Azure.Test.Perf/PerfProgram.cs

@@ -444,8 +444,9 @@ private static async Task RunTestsAsync(IPerfTest[] tests, PerfOptions options,
             var cpuTime = (Process.GetCurrentProcess().TotalProcessorTime - startCpuTime).TotalMilliseconds;
             var cpuPercentage = (cpuTime / cpuElapsed) / Environment.ProcessorCount;
 
-            Console.WriteLine($"Completed {totalOperations:N0} operations in a weighted-average of {weightedAverageSeconds:N2}s " +
-                $"({operationsPerSecond:N2} ops/s, {secondsPerOperation:N3} s/op, {cpuPercentage * 100:N2}% CPU)");
+            Console.WriteLine($"Completed {totalOperations:N0} operations in a weighted-average of {NumberFormatter.Format(weightedAverageSeconds, 4)}s " +
+                $"({NumberFormatter.Format(operationsPerSecond, 4)} ops/s, {NumberFormatter.Format(secondsPerOperation, 4)} s/op, " +
+                $"{NumberFormatter.Format(cpuPercentage * 100, 2)}% CPU)");
             Console.WriteLine();
 
             if (latency)