On Alpha and Integrity server systems, starts the Fast I/O
    operation. The $IO_PERFORM service completes asynchronously.
    For synchronous completion, use the Perform Fast I/O and Wait
    ($IO_PERFORMW) service.

    This service accepts 64-bit addresses.

    Format

      SYS$IO_PERFORM  fandle ,chan ,iosadr ,bufadr ,buflen ,devdata

    C Prototype

      int sys$io_perform  (unsigned __int64 fandl, unsigned short int

                          chan, struct _iosa *iosadr, void *bufadr,

                          unsigned __int64 buflen, unsigned __int64

                          devdata);