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NAME    [Toc]    [Back]

       sys_attrs_rt - rt subsystem attributes

DESCRIPTION    [Toc]    [Back]

       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 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()

              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

              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

              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

              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

SEE ALSO    [Toc]    [Back]


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