NAME

     atm_setbatchsize, atm_getbatchsize  - set/get batch size for
     null AAL interface

SYNOPSIS

     #include <fore_atm/fore_atm_user.h>

     int atm_setbatchsize(fd, batch_size)
     int fd;
     int batch_size;

     int atm_getbatchsize(fd, batch_size)
     int fd;
     int *batch_size;

DESCRIPTION

     atm_setbatchsize() is used to  set  the  minimum  number  of
     cells  that  must be received by the connection specified by
     fd before atm_recv(4N) will return.  Note that for  the  200
     series  adapters,  any  change  in  the ATM cell header will
     trigger a return.  This interface only applies to  ATM  con-
     nections  established  with  an  AAL of type aal_null.  When
     several PVCs are associated with the  same  descriptor,  the
     same  size  applies to each PVC.  By default, the batch size
     is set to 1, which causes atm_recv(4N) to return  each  cell
     received for the incoming connection specified by fd. A dif-
     ferent size can be specified using the  batch_size  argument
     to  atm_setbatchsize().  Setting  the  batch size to a value
     other than 1 can improve performance by reducing  the  over-
     head  incurred per cell.  The value must be chosen carefully
     since a batch size other than 1 will prevent data from  mov-
     ing  from  the  physical  level  to  the ATM level until the
     number of cells received for the connection is equal  to  or
     greater  than  the  batch  size.   In addition, care must be
     taken to ensure that the data size, in bytes (56  bytes  per
     cell  for  100  series  adapters,  48 bytes per cell for 200
     series adapters), is not greater than the Maximum  Transmis-
     sion Unit (MTU) for the connection.  The MTU for the link is
     returned by the atm_open(4N) operation.

     atm_getbatchsize() returns the current value  of  the  batch
     size in the batch_size argument.

RETURN VALUES

     atm_setbatchsize() and atm_getbatchsize() return 0  on  suc-
     cess.  On failure, they return -1 and set atm_errno to indi-
     cate the error. atm_error(4N) can be used to  print  a  text
     description  of errors of returned by atm_setbatchsize() and
     atm_getbatchsize().

ERRORS

     atm_setbatchsize() and atm_getbatchsize() can also fail with
     errors returned from the ioctl(2) system call.

SEE ALSO

     atm_intro(4N)