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sys_attrs_rt(5)						      sys_attrs_rt(5)


  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. There-
      fore, 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	for-

      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

      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

      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.

  * rttimer_max_num
      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 pro-

      Default: 64 (siginfo structures per process)

      Minimum: 0

      Maximum: 32,767