RAM Cache Test

RAMCacheTest.java

// dependency: graphhopper 0.3
// JVM_OPTS="-Xms2400m -Xmx2400m"
// 
// result on my oldish machine:
// separate arrays: GET=34.10 and SET=36.34
// single    array: GET=36.34 and SET=34.49
//
// => GET is ~7% faster for single array
// => SET is ~5% faster for single array
//
// important: you cannot compare GET and SET because of the '+'
class RAMCacheTest 
{
    public static void main( String[] args )
    {
        final int SIZE = 100 * 1000 * 1000;
        final int ITER = 10;

        Directory dir = new RAMDirectory();
        final DataAccess da1 = dir.find("test1");
        da1.create(4 * SIZE);
        final DataAccess da2 = dir.find("test2");
        da2.create(4 * SIZE);
        final DataAccess daCombined = dir.find("combined");
        daCombined.create(2 * 4 * SIZE);
        System.out.println("mem " + Helper.getMemInfo());

        MiniPerfTest res1 = new MiniPerfTest()
        {
            @Override
            public int doCalc( boolean warmup, int run )
            {
                for (int i = 0; i < SIZE; i++)
                {
                    long tmp = 4L * i;
                    da1.setInt(tmp, run++);
                    da2.setInt(tmp, -run);
                }

                return 0;
            }
        }.setIterations(ITER).start();

        System.out.println("[separ] per SET call:" + (res1.getMean() / SIZE) * 2000000f + "ns");

        MiniPerfTest res2 = new MiniPerfTest()
        {
            @Override
            public int doCalc( boolean warmup, int run )
            {
                int res = 0;
                for (int i = 0; i < SIZE; i++)
                {
                    long tmp = 4L * i;
                    res += da1.getInt(tmp) + da2.getInt(tmp);
                }

                return res;
            }
        }.setIterations(ITER).start();

        System.out.println("[separ] per GET call:" + (res2.getMean() / SIZE) * 2000000f + "ns");

        MiniPerfTest res3 = new MiniPerfTest()
        {
            @Override
            public int doCalc( boolean warmup, int run )
            {
                for (int i = 0; i < SIZE; i++)
                {
                    long tmp = 8L * i;
                    daCombined.setInt(tmp, run++);
                    daCombined.setInt(tmp + 4, -run);
                }

                return 0;
            }
        }.setIterations(ITER).start();

        System.out.println("[combi] per SET call:" + (res3.getMean() / SIZE) * 2000000f + "ns");

        MiniPerfTest res4 = new MiniPerfTest()
        {
            @Override
            public int doCalc( boolean warmup, int run )
            {
                int res = 0;
                for (int i = 0; i < SIZE; i++)
                {
                    long tmp = 8L * i;
                    res += daCombined.getInt(tmp) + daCombined.getInt(tmp + 4);
                }

                return res;
            }
        }.setIterations(ITER).start();

        System.out.println("[combi] per GET call:" + (res4.getMean() / SIZE) * 2000000f + "ns");
    }
}