aio_init


SYNOPSIS
       #define _GNU_SOURCE         /* See feature_test_macros(7) */
       #include <aio.h>

       void aio_init(const struct aioinit *init);

       Link with -lrt.

DESCRIPTION
       The  GNU-specific aio_init() function allows the caller to provide tun-
       ing hints to the glibc POSIX AIO implementation.  Use of this  function
       is  optional,  but  to be effective, it must be called before employing
       any other functions in the POSIX AIO API.

       The tuning information is provided in the  buffer  pointed  to  by  the
       argument init.  This buffer is a structure of the following form:

           struct aioinit {
               int aio_threads;    /* Maximum number of threads */
               int aio_num;        /* Number of expected simultaneous
                                      requests */
               int aio_locks;      /* Not used */
               int aio_usedba;     /* Not used */
               int aio_debug;      /* Not used */
               int aio_numusers;   /* Not used */
               int aio_idle_time;  /* Number of seconds before idle thread
                                      terminates (since glibc 2.2) */
               int aio_reserved;
           };

       The following fields are used in the aioinit structure:

       aio_threads    This  field  specifies  the  maximum  number  of  worker
                      threads that may be used by the implementation.  If  the
                      number of outstanding I/O operations exceeds this limit,
                      then excess operations will be  queued  until  a  worker
                      thread  becomes free.  If this field is specified with a
                      value less than 1, the value 1  is  used.   The  default
                      value is 20.

       aio_num        This field should specify the maximum number of simulta-
                      neous I/O requests that the caller expects  to  enqueue.
                      If  a value less than 32 is specified for this field, it
                      is rounded up to 32.  The default value is 64.

       aio_idle_time  This field specifies the amount of time in seconds  that
                      a  worker thread should wait for further requests before
                      terminating, after having completed a previous  request.
                      The default value is 1.

VERSIONS
       The aio_init() function is available since glibc 2.1.


Linux                             2010-10-06                       AIO_INIT(3)
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