Added Benchmarking tools (#413)

Added files for the smaller workload benchmarks

Added benchmark examples

Started implementing benchmarking functions

1 files changed, 100 insertions, 0 deletions

diff --git a/opendc-experiments/opendc-experiments-base/src/jmh/kotlin/org/opendc/experiments/JfrHeapAnalyzer.kt b/opendc-experiments/opendc-experiments-base/src/jmh/kotlin/org/opendc/experiments/JfrHeapAnalyzer.kt
new file mode 100644
index 00000000..ab57b736
--- /dev/null
+++ b/opendc-experiments/opendc-experiments-base/src/jmh/kotlin/org/opendc/experiments/JfrHeapAnalyzer.kt
@@ -0,0 +1,100 @@
+/*
+ * Copyright (c) 2026 AtLarge Research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.opendc.experiments
+
+import jdk.jfr.consumer.RecordingFile
+import java.nio.file.Path
+import kotlin.math.sqrt
+
+/**
+ * Heap usage statistics derived from a single JFR recording.
+ *
+ * All memory values are in megabytes and are computed from the `heapUsed` field
+ * of `jdk.GCHeapSummary` events captured during one JMH iteration.
+ *
+ * @property avgMb Mean heap usage across all GC samples in the recording (MB).
+ * @property maxMb Peak heap usage observed in any single GC sample (MB).
+ * @property stdMb Population standard deviation of heap usage across all samples (MB).
+ * @property sampleCount Number of `jdk.GCHeapSummary` events found in the recording.
+ */
+data class HeapStats(
+    val avgMb: Double,
+    val maxMb: Double,
+    val stdMb: Double,
+    val sampleCount: Int,
+)
+
+/**
+ * Parses a JFR recording file and computes heap usage statistics from its
+ * `jdk.GCHeapSummary` events.
+ *
+ * Each `jdk.GCHeapSummary` event is emitted by the JVM after a GC cycle and
+ * carries the `heapUsed` value (bytes). This function collects all such values,
+ * then computes mean, peak, and standard deviation, converting the results from
+ * bytes to megabytes.
+ *
+ * @param jfrPath Path to the `.jfr` recording file to analyze.
+ * @return A [HeapStats] instance if at least one `jdk.GCHeapSummary` event was
+ *   found, or `null` if the recording contained no such events (e.g., no GC
+ *   occurred during the iteration).
+ */
+fun analyzeHeap(jfrPath: Path): HeapStats? {
+    val samples = mutableListOf<Long>()
+
+    RecordingFile(jfrPath).use { recording ->
+        while (recording.hasMoreEvents()) {
+            val event = recording.readEvent()
+            if (event.eventType.name == "jdk.GCHeapSummary") {
+                samples.add(event.getLong("heapUsed"))
+            }
+        }
+    }
+
+    if (samples.isEmpty()) return null
+
+    val avg = samples.average()
+    val max = samples.max().toDouble()
+    val std = sqrt(samples.sumOf { (it - avg).let { d -> d * d } } / samples.size)
+    val toMb = 1.0 / (1024.0 * 1024.0)
+
+    return HeapStats(avg * toMb, max * toMb, std * toMb, samples.size)
+}
+
+/**
+ * Standalone entry point for inspecting the heap statistics of an existing JFR file.
+ *
+ * Reads `build/bench.jfr` (the default output path used by [OpenDCBenchmark]) and
+ * prints a human-readable summary to stdout. Useful for quickly inspecting the
+ * recording from the most recently completed benchmark iteration without re-running
+ * the full benchmark.
+ *
+ * Exits with an error if the file contains no `jdk.GCHeapSummary` events.
+ */
+fun main() {
+    val path = Path.of("build/bench.jfr")
+    val stats = analyzeHeap(path) ?: error("No jdk.GCHeapSummary events found in $path")
+    println("Heap statistics from $path (${stats.sampleCount} GC samples):")
+    println("  Avg: ${"%.2f".format(stats.avgMb)} MB")
+    println("  Max: ${"%.2f".format(stats.maxMb)} MB")
+    println("  Std: ${"%.2f".format(stats.stdMb)} MB")
+}