MemEval.java

package namespace;

public class Eval {

    public static final int INT, SHORT, BYTE, CHAR, LONG, FLOAT, DOUBLE;

    private static final int KB, MB, GB;
    public static final int ARRAY_MIN, ARRAY_MAX;
    public static int[] x;

    static {
        INT = Integer.SIZE / Byte.SIZE;
        SHORT = Short.SIZE / Byte.SIZE;
        BYTE = 1;
        CHAR = Character.SIZE / Byte.SIZE;
        LONG = Long.SIZE / Byte.SIZE;
        FLOAT = Float.SIZE / Byte.SIZE;
        DOUBLE = Double.SIZE / Byte.SIZE;

        KB = 1024;
        MB = (int) Math.pow(KB, 2);
        GB = MB * KB;

        ARRAY_MIN = KB;
        ARRAY_MAX = (int) Math.pow(KB * 4, 2);
        x = new int[ARRAY_MAX];
    }

    public static double getSeconds() {
        return System.nanoTime() / 1e9;
    }

    public static int label(int i) {
        if (i < 1e3)
            printf("%1dB,", i);
        else if (i < 1e6)
            printf("%1dK,", i / KB);
        else if (i < 1e9)
            printf("%1dM,", i / MB);
        else
            printf("%1dG,", i / GB);

        return 0;
    }

    public static void main(String[] args) {
        int nextstep, i, index, stride;
        int csize;
        double steps, tsteps;
        double loadtime, lastsec, sec0, sec1 = 0, sec = 0;

        /* Initialize output */
        printf(" ,");
        for (stride = 1; stride <= ARRAY_MAX / 2; stride *= 2)
            label((int)(stride*sizeof(int.class)));
        printf("\n");

        /* Main loop for each configuration */
        for (csize = ARRAY_MIN; csize <= ARRAY_MAX; csize *= 2) {
            label(csize * sizeof(int.class)); /* Print cache size for this loop */
            for (stride = 1; stride <= csize / 2; stride *= 2) {
                /* Layout path of memory references in array */
                for (index = 0; index < csize; index += stride)
                    x[index] = index + stride; /* Pointer to next */
                x[index - stride] = 0;

                /* Wait for timer to roll over */
                lastsec = getSeconds();
                do sec0 = getSeconds(); while (sec0 == lastsec);

                /* Walk through path in array for twenty seconds */
                /* This gives 5% accuracy with second resolution */
                steps = 0.0; /* Number of steps taken */
                nextstep = 0; /* Start at beginning of path */
                sec0 = getSeconds(); /* Start timer */
                do  { /* Repeat for 20 seconds */
                    for (i=stride; i != 0; i--) { /* Keep sample size */
                         nextstep = 0;
                         do nextstep = x[nextstep];
                         while (nextstep != 0);
                    }
                    steps++;
                    sec1 = getSeconds();
                } while ((sec1 - sec0) < 20f);
                sec = sec1 - sec0;

                /* Repeat empty loop to loop subtracted overhead */
                tsteps = 0.0; /* used to match no. while iterations */
                sec0 = getSeconds(); /* Start timer */
                do {
                    for (i=stride; i != 0; i--) { /* Keep sample size */
                        index = 0;
                        do index += stride;
                        while (index < csize);
                    }
                    tsteps++;
                    sec1 = getSeconds();
                } while (tsteps < steps);
                sec -= (sec1 - sec0);
                loadtime = (sec * 1e9) / (steps * csize);

                /* Write out results in CSV format */
                printf("%4.1f,", loadtime < 0.1 ? 0.1 : loadtime);
            } /* End of inner loop */
            System.out.println();
        } /* End of outer loop */
    }

    /** Utility function to emulate c functionality */

    public static void printf(String format, Object... args) {
        System.out.printf(format, args);
    }

    public static int sizeof(Class<?> dataType) {
        if (dataType == null)
            throw new NullPointerException();

        if (dataType == int.class    || dataType == Integer.class)   return INT;
        if (dataType == short.class  || dataType == Short.class)     return SHORT;
        if (dataType == byte.class   || dataType == Byte.class)      return BYTE;
        if (dataType == char.class   || dataType == Character.class) return CHAR;
        if (dataType == long.class   || dataType == Long.class)      return LONG;
        if (dataType == float.class  || dataType == Float.class)     return FLOAT;
        if (dataType == double.class || dataType == Double.class)    return DOUBLE;

        return INT;
    }
}