WC-Write Combining 合并写技术

WC-Write Combining 合并写技术
为了提高写效率: CPU在写入L1时，同时用WC写入L2

实验代码：

public class WriteCombining {
    private static final int    ITERATIONS = Integer.MAX_VALUE;
    private static final int    ITEMS      = 1 << 24;
    private static final int    MASK       = ITEMS - 1;

    private static final byte[] arrayA     = new byte[ITEMS];
    private static final byte[] arrayB     = new byte[ITEMS];
    private static final byte[] arrayC     = new byte[ITEMS];
    private static final byte[] arrayD     = new byte[ITEMS];
    private static final byte[] arrayE     = new byte[ITEMS];
    private static final byte[] arrayF     = new byte[ITEMS];

    public static void main(final String[] args) {
        for (int i = 1; i <= 2; i++) {
            System.out.println(i + " SingleLoop duration (ns) = " + runCaseOne());
            System.out.println(i + " SplitLoop  duration (ns) = " + runCaseTwo());
        }
    }

    public static long runCaseOne() {
        long start = System.nanoTime();
        int i = ITERATIONS;

        while (--i != 0) {
            int slot = i & MASK;
            byte b = (byte) i;
            arrayA[slot] = b;
            arrayB[slot] = b;
            arrayC[slot] = b;
            arrayD[slot] = b;
            arrayE[slot] = b;
            arrayF[slot] = b;
        }
        return System.nanoTime() - start;
    }

    public static long runCaseTwo() {
        long start = System.nanoTime();
        int i = ITERATIONS;
        while (--i != 0) {
            int slot = i & MASK;
            byte b = (byte) i;
            arrayA[slot] = b;
            arrayB[slot] = b;
            arrayC[slot] = b;
        }
        i = ITERATIONS;
        while (--i != 0) {
            int slot = i & MASK;
            byte b = (byte) i;
            arrayD[slot] = b;
            arrayE[slot] = b;
            arrayF[slot] = b;
        }
        return System.nanoTime() - start;
    }
}