sys_attrs_rt(5)sys_attrs_rt(5)NAMEsys_attrs_rt - rt subsystem attributes
DESCRIPTION
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 modi‐
fied 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 cur‐
rently 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 instruc‐
tions.
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 oper‐
ating 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
SEE ALSOsys_attrs(5)sys_attrs_rt(5)
