How can I speed up packet capturing and packet send with jpcap

Question

DSP send raw ethernet packets to PC than PC capturing these packets and send ack response. They are messaging MAC to MAC so there are no ip layer. I want to make real-time messaging in every 1ms. DSP send message every 1 milisecond but PC can not capture the messages and send reply under 1 milisecond. Capturing and sending packet takes 15 - 30 ms. This result too slow for me. How can I make this faster. I am using jpcap library and my operating system Win XP x32.

Capturing Code:

    private void captor() {
                try {
                    captor = JpcapCaptor.openDevice(cf.getDevice(), 100, true, 1);
                } catch (Exception ex) {
                    Logger.getLogger(CapturingPacket.class.getName()).log(Level.SEVERE, null, ex);
                }
            }



    private void capturing() {
            Packet packet = captor.getPacket();
            if (packet != null) {
                if (packet.data.length > 0) {
                    EthernetPacket ethernetPacket = (EthernetPacket) packet.datalink;                
                    String receivedDestMac = Common.byteToMacStringFormat(ethernetPacket.src_mac);

                    if (definedDestMac.equals(receivedDestMac)) {
                        captured(packet.data);
                    }

                }
            }

}

private class captureRunner implements Runnable {

        public void run() {
            captor();
            while (running) {
                capturing();
                try {
                    Thread.sleep(0);
                } catch (InterruptedException err) {
                }
            }
        }
    }

Sending Code:

private void send(byte[] message) {
        try {

            JpcapSender send = JpcapSender.openDevice(cf.getDevice());

            Packet packet = new Packet();
            //ethernet frame
            EthernetPacket ethernetPacket = new EthernetPacket();

            // #dst_mac
            ethernetPacket.dst_mac = getDestMac();
            // #src_mac
            ethernetPacket.src_mac = cf.getDevice().mac_address;
            // #frametype
            ethernetPacket.frametype = Common.ETHERNET_FRAME_TYPE;
            // #data
            packet.data = message;
            // datalink
            packet.datalink = ethernetPacket;
            send.sendPacket(packet);
            send.close();

        } catch (Exception ex) {
            Common.showErrorMessage("Send Error");
            Logger.getLogger(MessagingPacket.class.getName()).log(Level.SEVERE, null, ex);
        }

    }

Answer 1

"Capturing and sending packet takes 15 - 30 ms." -- This is normal. You cannot make this much faster. Windows is not a real-time operating system. Use a microcontroller instead (there are better options, like FPGA and ARM, but I have no experience with these).

Answer 2

Use a libpcap filter, which you can set via JPcap, instead of your Java filter. That way non-matching packets won't even be captured, let alone cause callbacks into JPcap and then your Java code.

Also use a much bigger buffer than 100.