sys_attrs_rt - rt subsystem attributes
This reference page lists and describes attributes for the
Realtime (rt) kernel subsystem. Refer to sys_attrs(5) for
an introduction to the topic of kernel subsystem
attributes.
Attributes whose names are preceded with an asterisk (*)
can be modified without rebooting the system.
The maximum number of asynchronous I/O requests
supported on the list initiated by the lio_listio()
function.
Default: 64 (requests)
Minimum: 64
Maximum: 256
The maximum percentage of physical memory that AIO
structures can occupy. The value of this attribute
is used to scale back aio_task_max_num when that is
set too high for the system.
Default: 1 (percent)
Minimum: 0
Maximum: 10
The aio_max_percent attribute is not useful on
today's servers, most of which have a large amount
of memory. Even 1 percent of physical memory is too
high a limit for many of the servers currently in
use. Therefore, it is recommended that, if you need
to tune any settings related to the amount of wired
physical memory used for AIO structures, it is more
practical to use the aio_max_retry,
aio_retry_scale, and aio_task_max_num attributes.
The number of additional attempts made on behalf of
a process to wire AIO buffers to physical memory if
the system maximum for wired physical memory has
already been reached or if the attempt to wire
additional physical memory would cause that maximum
to be exceeded. By default, if a process attempts
to wire physical memory for AIO buffers and this
would exceed the system maximum, an error is
returned.
Default: 0 (no retries)
Minimum: 0
Maximum: 256
The time interval between attempts made for a process
to wire AIO buffers to physical memory when
the system is at its maximum for wired physical
memory. The time interval is calculated by the following
formula:
Hz / aio_retry_scale
Default: 4 (0.25 seconds when Hz is equal to 1)
Minimum: 1
Maximum: 1024
This attribute has no effect when aio_max_retry is
set to 0 (the default).
Enables (1) or disables (0) AIO write requests
through connected sockets.
Default value: 1 (enabled)
Do not change the default setting for this
attribute unless instructed to do so by support
personnel or patch kit instructions.
A limit that indirectly controls the number of AIO
requests that can be wired in physical memory by
restricting the amount of wired physical memory
available for a specified number of tasks. One page
of wired physical memory is available to the number
of tasks specified by aio_task_max_num.
Default: 102 (one page of wired memory per 102
tasks)
Minimum: 0
Maximum: 2,147,483,647
This attribute has no effect. It is not currently
used by operating system software and will be
removed in a future release.
The maximum number of POSIX realtime timers per
task or process.
Default: 32 (timers)
Minimum: 32
Maximum: 8192
This attribute can be modified at run time but will
affect only the processes that start up after the
change is made. If you want the change to affect a
process that is already running, you must stop and
restart the process.
The maximum number of siginfo structures that can
be queued to a process.
Default: 64 (siginfo structures per process)
Minimum: 0
Maximum: 32,767
sys_attrs(5)
sys_attrs_rt(5)
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