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8346470: Improve WriteBarrier JMH to have old-to-young refs

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Reviewed-by: tschatzl
This commit is contained in:
Eric Caspole 2025-03-13 18:32:15 +00:00
parent b50fe9b8cc
commit 03ef79cf05
1 changed files with 93 additions and 2 deletions
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95
test/micro/org/openjdk/bench/vm/compiler/WriteBarrier.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2014, 2024, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -26,12 +26,14 @@ import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.CompilerControl;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Level;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.TearDown;
import org.openjdk.jmh.annotations.Warmup;
import java.util.Random;
@ -56,12 +58,18 @@ public abstract class WriteBarrier {
private Object[] theArrayLarge;
private int[] indicesLarge;
private Object[] youngArraySmall;
private Object[] youngArrayLarge;
private Object nullRef;
private Object realRef;
private Object youngRef;
// For field update tests
public Referencer head = null;
public Referencer tail = null;
public Referencer youngHead = null;
public Referencer youngTail = null;
// For random number generation
private int m_w;
@ -81,7 +89,7 @@ public abstract class WriteBarrier {
}
}
@Setup
@Setup(Level.Trial)
public void setup() {
theArraySmall = new Object[NUM_REFERENCES_SMALL];
indicesSmall = new int[NUM_REFERENCES_SMALL];
@ -114,6 +122,16 @@ public abstract class WriteBarrier {
System.gc();
}
@Setup(Level.Iteration)
public void setupIteration() {
// Reallocate target objects each iteration to ensure they are in young gen.
youngArraySmall = new Object[NUM_REFERENCES_SMALL];
youngArrayLarge = new Object[NUM_REFERENCES_LARGE];
youngRef = new Object();
this.youngHead = new Referencer();
this.youngTail = new Referencer();
}
private int get_random() {
m_z = 36969 * (m_z & 65535) + (m_z >> 16);
m_w = 18000 * (m_w & 65535) + (m_w >> 16);
@ -133,6 +151,70 @@ public abstract class WriteBarrier {
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void testArrayWriteBarrierFastPathOldToYoungSmall() {
for (int i = 0; i < NUM_REFERENCES_SMALL; i++) {
youngArraySmall[indicesSmall[NUM_REFERENCES_SMALL - i - 1]] = realRef;
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void testArrayWriteBarrierFastPathYoungToOldSmall() {
for (int i = 0; i < NUM_REFERENCES_SMALL; i++) {
theArraySmall[indicesSmall[NUM_REFERENCES_SMALL - i - 1]] = youngRef;
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void testArrayWriteBarrierFastPathYoungToYoungSmall() {
for (int i = 0; i < NUM_REFERENCES_SMALL; i++) {
youngArraySmall[indicesSmall[NUM_REFERENCES_SMALL - i - 1]] = youngRef;
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void testArrayWriteBarrierFastPathNullYoungSmall() {
for (int i = 0; i < NUM_REFERENCES_SMALL; i++) {
youngArraySmall[indicesSmall[NUM_REFERENCES_SMALL - i - 1]] = nullRef;
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void testArrayWriteBarrierFastPathOldToYoungLarge() {
for (int i = 0; i < NUM_REFERENCES_LARGE; i++) {
youngArrayLarge[indicesLarge[NUM_REFERENCES_LARGE - i - 1]] = realRef;
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void testArrayWriteBarrierFastPathYoungToYoungLarge() {
for (int i = 0; i < NUM_REFERENCES_LARGE; i++) {
youngArrayLarge[indicesLarge[NUM_REFERENCES_LARGE - i - 1]] = youngRef;
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void testArrayWriteBarrierFastPathNullYoungLarge() {
for (int i = 0; i < NUM_REFERENCES_LARGE; i++) {
youngArrayLarge[indicesLarge[NUM_REFERENCES_LARGE - i - 1]] = nullRef;
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void testArrayWriteBarrierFastPathYoungToOldLarge() {
for (int i = 0; i < NUM_REFERENCES_LARGE; i++) {
theArrayLarge[indicesLarge[NUM_REFERENCES_LARGE - i - 1]] = youngRef;
}
}
@Benchmark
@CompilerControl(CompilerControl.Mode.DONT_INLINE)
public void testArrayWriteBarrierFastPathNullSmall() {
@ -166,6 +248,15 @@ public abstract class WriteBarrier {
this.tail.clear();
}
@Benchmark()
public void testFieldWriteBarrierFastPathYoungRef() {
// Shuffle everything around
this.tail.append(this.youngHead);
this.head.clear();
this.head.append(this.youngTail);
this.tail.clear();
}
// This run is useful to compare different GC barrier models without being
// affected by C2 unrolling the main loop differently for each model.
@Fork(value = 3, jvmArgs = {"-XX:LoopUnrollLimit=1"})