FalseSharingCacheLinePaddingBenchmark.java

package com.lmax.disruptor;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Group;
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.State;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.concurrent.TimeUnit;

@BenchmarkMode(Mode.Throughput)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS)
@Fork(5)
public class FalseSharingCacheLinePaddingBenchmark
{
    @State(Scope.Group)
    public static class StateBaseline
    {
        long readOnly;
        long writeOnly;
    }

    @Benchmark
    @Group("baseline")
    public long reader(StateBaseline s)
    {
        return s.readOnly;
    }

    @Benchmark
    @Group("baseline")
    public void writer(StateBaseline s)
    {
        s.writeOnly++;

    }


    @State(Scope.Group)
    public static class StateSingleCacheLinePadding
    {
        private static final int CACHE_LINE_IN_LONGS = 64 / Long.BYTES;
        private static final int ARRAY_SIZE_FOR_TWO_VALUES = CACHE_LINE_IN_LONGS * 2;
        private static final int READ_VALUE_INDEX = 0;
        private static final int WRITE_VALUE_INDEX = CACHE_LINE_IN_LONGS + 1;

        long[] arr = new long[ARRAY_SIZE_FOR_TWO_VALUES];
    }

    @Benchmark
    @Group("singleCacheLine")
    public long reader(StateSingleCacheLinePadding s) {
        return s.arr[StateSingleCacheLinePadding.READ_VALUE_INDEX];
    }

    @Benchmark
    @Group("singleCacheLine")
    public void writer(StateSingleCacheLinePadding s) {
        s.arr[StateSingleCacheLinePadding.WRITE_VALUE_INDEX]++;
    }


    @State(Scope.Group)
    public static class StateDoubleCacheLinePadding
    {
        private static final int CACHE_LINE_IN_LONGS = 64 / Long.BYTES;
        private static final int ARRAY_SIZE_FOR_TWO_VALUES = CACHE_LINE_IN_LONGS * 4;
        private static final int READ_VALUE_INDEX = 0;
        private static final int WRITE_VALUE_INDEX = (CACHE_LINE_IN_LONGS * 2) + 1;

        long[] arr = new long[ARRAY_SIZE_FOR_TWO_VALUES];
    }

    @Benchmark
    @Group("doubleCacheLine")
    public long reader(StateDoubleCacheLinePadding s) {
        return s.arr[StateDoubleCacheLinePadding.READ_VALUE_INDEX];
    }

    @Benchmark
    @Group("doubleCacheLine")
    public void writer(StateDoubleCacheLinePadding s) {
        s.arr[StateDoubleCacheLinePadding.WRITE_VALUE_INDEX]++;
    }


    public static void main(String[] args) throws RunnerException
    {
        Options opt = new OptionsBuilder()
                .include(FalseSharingCacheLinePaddingBenchmark.class.getSimpleName())
                .threads(Runtime.getRuntime().availableProcessors())
                .build();

        new Runner(opt).run();
    }
}