max_mem_window(5) max_mem_window(5)
Tunable Kernel Parameters
NAME [Toc] [Back]
max_mem_window - maximum number of group-private 32-bit shared memory
configurable by users
VALUES [Toc] [Back]
Default
0
Allowed values [Toc] [Back]
Minimum: 0 shared memory windows
Maximum: 65535 shared memory windows
DESCRIPTION [Toc] [Back]
32-bit processes usually share the global quadrants 3 and 4 for such
things as I/O mappings, shared libraries, shared mapped files, etc.
However, you may wish to use quadrant 3 in a more limited sharing
fashion with only a select group of processes. Memory windows allow
this functionality.
If this tunable is set to 0, 32-bit programs always use the global Q3
and Q4 for shared memory. If this tunable is greater than 0 processes
in defined groups use a Q3 private to that group, and then the
globally shared Q4 if Q3 is full.
Who is Expected to Change This Tunable?
Anyone.
Restrictions on Changing [Toc] [Back]
Changes to this tunable take effect at the next reboot.
When Should the Value of This Tunable Be Raised?
This tunable should be raised if more group-private Q3 areas are
needed by the users of the system. Each memory window in active use
will require approximately 1Mb of kernel memory. Windows no longer in
use will have this memory reclaimed by the system.
What Are the Side Effects of Raising the Value?
A little more memory is used in the kernel.
When Should the Value of This Tunable Be Lowered?
If process groups are not being used, or not being used in the
quantity set by the tunable, there is really no point to having this
value higher than what is actually needed.
What Are the Side Effects of Lowering the Value?
The kernel uses a little less memory. If the value is set to 0, no
group-private Q3's are allowed.
What Other Tunable Values Should Be Changed at the Same Time?
None.
Hewlett-Packard Company - 1 - HP-UX 11i Version 2: Sep 2004
max_mem_window(5) max_mem_window(5)
Tunable Kernel Parameters
WARNINGS [Toc] [Back]
All HP-UX kernel tunable parameters are release specific. This
parameter may be removed or have its meaning changed in future
releases of HP-UX.
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
values. For information about the effects of installation on tunable
values, consult the documentation for the kernel software being
installed. For information about optional kernel software that was
factory installed on your system, see HP-UX Release Notes at
http://docs.hp.com.
AUTHOR [Toc] [Back]
max_mem_window was developed by HP.
SEE ALSO [Toc] [Back]
getmemwindow(1M), services.window(4), setmemwindow(1M).
Hewlett-Packard Company - 2 - HP-UX 11i Version 2: Sep 2004 [ Back ] |