AIO_SGI_INIT(3)						       AIO_SGI_INIT(3)

NAME    [Toc]    [Back]

     aio_sgi_init, aio_sgi_init64 - asynchronous I/O initialization

C SYNOPSIS    [Toc]    [Back]

     #include <aio.h>

     void aio_sgi_init(aioinit_t *);

     void aio_sgi_init64(aioinit_t *);

DESCRIPTION    [Toc]    [Back]

     The optional aio_sgi_init() function allows the calling process to
     initialize	the asynchronous I/O interface.	 If this function is not
     called, the asynchronous I/O interface is initialized the first time a
     call is made to aio_read(), aio_write() or	lio_listio(). aio_sgi_init()
     takes an aioinit_t	* as an	argument.  If this argument is NULL, default
     initialization values are used.  Initialization of	the interface includes
     starting up slave threads which are used to carry out I/O requests.  This
     is	significant if a process that runs isolated intends to use
     asynchronous I/O.	An explicit call to aio_sgi_init() prior to isolating
     will cause	the slave threads on non-isolated processors.  An explicit
     call to aio_sgi_init() or implicit	initialization of the interface	by
     calls to aio_read,	aio_write or lio_listio() from a process that is
     running on	an isolated processor cause the	aio threads to run on the same
     isolated processor	as the caller.

     The aioinit structure contains the	following fields:

     aio_threads: The number of	threads	that the aio library will use from
     user space.  While	the user can queue up many operations to be done by
     the aio library, they are currently passed	to the kernel one at a time by
     each thread.  The aio_threads value allows	the use	to pick	the level of
     parallelism that their application	needs. The current default is 5.

     aio_locks:	This is	used by	realtime programs to pre-allocate needed data
     structures	so that	real time programs do not need to allocate them	in
     critical areas. This should be set	to the maximum number of simultaneous
     lio_listio(LIO_NOWAIT), aio_fsync(), and aio_suspend() that your program
     will be executing.	Nothing	bad will happen	if you pick a number that is
     too small except that the program may need	to call	malloc,	and thus
     possibly cause problems for some realtime programs. The current default
     is	3

     aio_numusers: Due to its use of IRIX semaphores (see usconfig(3P))	Multi
     threaded programs must pass the number of sprocs or pthreads that the
     application contains to the AIO library. Passing a	number that is too
     small can result in program deadlocks and other errors. The current
     default is	5.

     aio_num, aio_debug, and aio_reserved are currently	unused and ignored.
     aio_usedba	is used	by a few specific applications,	and all	other programs
     must set it to zero for correct operation.



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AIO_SGI_INIT(3)						       AIO_SGI_INIT(3)



     The aio_sgi_init64() routine is identical to aio_sgi_init() except	that
     it	takes an aioinit64_t * (see <aio.h>) as	an argument.  It should	be
     used for explicit initialization of parameters used by aio_read64(),
     aio_write64() and lio_listio64().

SEE ALSO    [Toc]    [Back]

     aio_write(3), lio_listio(3), aio_error(3),	aio_return(3), aio_cancel(3),
     mpadmin(1), realtime(5).


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