aio_monitor_run_sec man page on HP-UX

Man page or keyword search:  
man Server   10987 pages
apropos Keyword Search (all sections)
Output format
HP-UX logo
[printable version]

aio_monitor_run_sec(5)					aio_monitor_run_sec(5)

       aio_monitor_run_sec  -  frequency  of AIO thread pool monitor execution
       (in seconds)

   Allowed values
   Recommended values
       The implementation of POSIX AIO on HP-UX uses kernel threads to perform
       I/Os to filesystems that do not directly support true asynchronous I/O.
       (This distinction is transparent to the user.)  The kernel threads  are
       organized into worker-thread pools (called AIO thread pools) created on
       a per-process basis.  Since a thread pool mechanism for I/Os introduces
       a  variety  of  trade-offs  concerning  utilization of CPU time vs. I/O
       resources, four dynamic tunables are available to customize the	behav‐
       ior of this thread pool: and Please see individual manpages for details
       on each of these tunables.

       The tunable specifies how frequently a process' AIO thread pool will be
       monitored.   Monitoring	involves  making  decisions  about  growing or
       shrinking the AIO thread pool based on the constraints specified by and

       Note that although the AIO thread pool can grow both on its own (as new
       I/Os  are issued) or as a result of the monitoring mechanism, the moni‐
       toring mechanism is the primary method by which	the  thread  pool  can
       shrink.	 So  this  tunable  effectively determines how quickly the AIO
       thread pool will adapt itself to a given I/O load.

   Who Is Expected to Change This Tunable?
       System administrators that run applications requiring  heavy  usage  of
       POSIX AIO to filesystems.

   Restrictions on Changing
       This  tunable is dynamic.  Changes to to this tunable take effect imme‐
       diately for new processes started after the change.  They  also	impact
       existing	 processes,  but the speed with which the changes propagate to
       running processes is determined by the former value of

   When Should the Value of This Tunable Be Raised?
       should be raised for applications that have steady I/O loads for	 which
       POSIX  AIO would rarely need to adapt.  Another possibility is applica‐
       tions with bursty or periodic I/O loads, that want POSIX AIO  to	 main‐
       tain a larger thread pool through periods of decreased I/O activity (to
       be ready for busier periods).  This can be accomplished	by  increasing
       this tunable to reduce the frequency of AIO monitor updates.

   What Are the Side Effects of Raising the Value of This Tunable?
       Increasing  this tunable will reduce the speed with which the POSIX AIO
       thread pool mechanism adapts itself to changing I/O loads.  This	 could
       cause  slightly	reduced	 performance  when applications first begin to
       issue POSIX AIOs.

   When Should the Value of This Tunable Be Lowered?
       should be lowered when applications want to  increase  the  speed  with
       which  the  POSIX  AIO  thread  pool  adapts itself to I/O loads.  This
       should generally maximize performance, except in the case of bursty I/O
       loads,  or I/O loads with periodic peaks, for which a slower adaptation
       may be desirable.

   What Are the Side Effects of Lowering the Value of This Tunable?
       The POSIX AIO thread pool will adjust  more  quickly  to	 changing  I/O
       loads,  so  new	threads will be spawned more quickly for new I/Os, and
       threads will be killed more quickly as I/O loads decrease.  Except  for
       bursty or periodic I/O loads, this should maximize performance.

   What Other Tunables Should Be Changed at the Same Time as This One?
       interacts  with this tunable by setting a strict limit on the number of
       threads that can be used for POSIX AIO.

       interacts with this tunable by setting a limit on the number of threads
       that  can  be  used for POSIX_AIO, but does so based on a percentage of
       the maximum number of allowable process threads.	 This allows  the  AIO
       thread pools to respond dynamically to changes in

       defines the desired relationship between the number of POSIX AIO kernel
       threads and the number of I/Os to be serviced.

       All HP-UX kernel tunable parameters are release specific.  This parame‐
       ter  may	 be  removed or have its meaning changed in future releases of

       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  val‐
       ues.  For information about the effects of installation on tunable val‐
       ues, consult the documentation for the kernel software being installed.
       For  information	 about	optional  kernel  software  that  was  factory
       installed on your system, see at

       was developed by HP.

       kctune(1M),  sam(1M),  gettune(2),   settune(2),	  aio_proc_threads(5),
       aio_proc_thread_pct(5), aio_req_per_thread(5).

			   Tunable Kernel Parameters	aio_monitor_run_sec(5)

List of man pages available for HP-UX

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
Vote for polarhome
Free Shell Accounts :: the biggest list on the net