aio_memlock(3aio)                                  aio_memlock(3aio)


       NAME
             aio_memlock - memory locking function

       SYNOPSIS
             cc [options] -D_REENTRANT file -lthread
             #include <aio.h>
             int aio_memlock(void *avaddr, size_t asize);

       DESCRIPTION
             aio_memlock provides a mechanism for locking the area of
             memory to be used for asynchronous I/O operations.

             An application must lock down the entire area of memory which
             will be accessed to transfer the data for each request.
             avaddr specifies the starting address of memory to lock.
             asize specifies the size of the area in bytes.

             Only one request to aio_memlock is permitted during a
             process's lifetime.  Once the memory is locked, it cannot be
             unlocked or changed.  No special privilege is needed for this
             operation.

          Errors
             EINVAL
                   avaddr and/or avsize are not valid or an attempt has
                   been made to lock memory more than once.

       USAGE
             You should only use aio_memlock with SVR4.2 or when the
             AIO_RAW aio_flag is set.

             The amount of locked memory must be sized carefully.  If it is
             too large, it may adversely effect the overall system
             performance.  If it is too small, it will limit the number of
             asynchronous I/O requests that can be outstanding at any given
             point in time.

             In addition, the application should make sure that any calls
             to functions that resize memory, such as brk and sbrk do not
             involve addresses within the locked area.

       REFERENCES
             aio_cancel(3aio), aiocb(5), aio_read(3aio), aio_suspend(3aio),
             write(2)




                           Copyright 1994 Novell, Inc.               Page 1