Monitoring UDP socket in glib (mm) increases CPU time

Question

Monitoring UDP socket in glib (mm) increases CPU time

I have a GTKmm Windows application (built-in with MinGW) that receives UDP packets (without sending). A socket is a native winsock, and I use the glibmm IOChannel to connect it to the main application loop. The socket is read from recvfrom.

My problem: this setting consumes 25% of the processor time on a 3GHz workstation. Can someone tell me why?

In this case, the application is inactive, and if I delete the UDP code, the processor load will drop to almost zero. Since the application needs to perform some intensive CPU tasks, I could better consider ways to spend 25%

Here are some code snippets: (sorry for printf;))


/* bind */
void UDPInterface::bindToPort(unsigned short port)
{
    struct sockaddr_in target;
    WSADATA wsaData;

    target.sin_family = AF_INET;
    target.sin_port = htons(port);
    target.sin_addr.s_addr = 0;

    if ( WSAStartup ( 0x0202, &wsaData ) )
    {
        printf("WSAStartup failed!\n");
        exit(0); // :)
        WSACleanup();
    }

    sock = socket( AF_INET, SOCK_DGRAM, 0 );
    if (sock == INVALID_SOCKET)
    {
        printf("invalid socket!\n");
        exit(0);
    }

    if (bind(sock,(struct sockaddr*) &target, sizeof(struct sockaddr_in) ) == SOCKET_ERROR)
    {
        printf("failed to bind to port!\n");
        exit(0);
    }

    printf("[UDPInterface::bindToPort] listening on port %i\n", port);
}

/* read */
bool UDPInterface::UDPEvent(Glib::IOCondition io_condition)
{
    recvfrom(sock, (char*)buf, BUF_SIZE*4, 0, NULL, NULL);
    /* process packet... */
}

/* glibmm connect */
Glib::RefPtr channel = Glib::IOChannel::create_from_win32_socket(udp.sock);
Glib::signal_io().connect( sigc::mem_fun(udp, &UDPInterface::UDPEvent), channel, Glib::IO_IN );