I'm wondering when the GatheringByteChannel's write methods (taking in an array of ByteBuffers) have advantages over the "regular" WritableByteChannel write methods.

I tried a test where I could use the regular vs. the gathering write method on a FileChannel, with approx 400KB/sec total in ByteBuffers of between 23-27 bytes in length in both cases. Gathering writes used an array of 64. The regular method used up approx 12% of my CPU, and the gathering method used up approx 16% of my CPU (worse than the regular method!)

This tells me it's NOT useful to use gathering writes on a FileChannel around this range of operating parameters. Why would this be the case, and when would you ever use GatheringByteChannel? (on network I/O?)

Relevant differences here:

public void log(Queue<Packet> packets) throws IOException
{
    if (this.gather)
    {
        int Nbuf = 64;
        ByteBuffer[] bbufs = new ByteBuffer[Nbuf];
        int i = 0;
        Packet p;
        while ((p = packets.poll()) != null)
        {
            bbufs[i++] = p.getBuffer();
            if (i == Nbuf)
            {
                this.fc.write(bbufs);
                i = 0;
            }
        }
        if (i > 0)
        {
            this.fc.write(bbufs, 0, i);
        }
    }
    else
    {
        Packet p;
        while ((p = packets.poll()) != null)
        {
            this.fc.write(p.getBuffer());
        }
    }
}