NAME
aio_max_ops — maximum number of POSIX async I/O operations that can be queued at any time
VALUES
Allowed values
The minimum value allowed is
2.
The maximum value allowed is
0x100000.
The value is further constrained in that it must be greater than or equal to
aio_listio_max.
Specify a positive integer value.
DESCRIPTION
This parameter places a limit on the system resources that can be
consumed if large numbers of POSIX asynchronous I/O operations are
queued on the system at the same time.
This parameter limits the
ability of competing processes to overwhelm the system with large
numbers of asynchronous I/O operations and the memory they require.
Each enqueued asynchronous operation requires allocation of system
memory for its internal control structure, thus making this limit
necessary.
In addition to the system-wide limit, there is a per-process
limit that is controlled using the argument
RLIMIT_AIO_OPS
to
getrlimit()
and
setrlimit()
calls.
aio_listio_max
limits the number of operations that can be contained in a single
listio()
call from a given process, and the value of
aio_max_ops
must be sufficient to meet the reasonable needs
of all processes that are making simultaneous or nearly simultaneous
listio()
calls without jeopardizing overall system
balance.
Who Is Expected to Change This Tunable?
System administrators that run applications requiring heavy usage of
POSIX AIO to file systems.
Restrictions on Changing
This tunable is dynamic
(tuning will take effect immediately on the running system).
What Other Tunables Should Be Changed at the Same Time as This One?
The value assigned to
aio_max_ops
must be greater than or equal to
aio_listio_max.
WARNINGS
All HP-UX kernel tunable parameters are release specific.
This parameter may be removed or have its meaning changed in
future releases of HP-UX.
Installation of optional kernel software, from HP or other vendors,
may cause changes to tunable parameter values. After installation,
some tunable parameters may no longer be at the default or
recommended values. For information about the effects of
installation on tunable values, consult the documentation
for the kernel software being installed.
For information about optional kernel software that was
factory installed on your system, see
HP-UX Release Notes
at
http://docs.hp.com.
AUTHOR
aio_max_ops
was developed by HP.
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