NAME
maxrsessiz, maxrsessiz_64bit — maximum size (in bytes) of the RSE stack for any user process on the Itanium-based platform
VALUES
Default
32 bit default: 0x800000 (8MB)
64 bit default: 0x800000 (8MB)
Allowed values
32 bit minimum: 0x40000
32 bit maximum: 0x17F00000
64 bit minimum: 0x40000
64 bit maximum: 0x40000000
DESCRIPTION
Itanium-based systems utilize a per-process register stack in main memory (for
more information see the Intel IA-64 Architecture Software Developer's
Manual, Volume 2, Chapter 6). This stack moves registers between
the physical registers and main memory and is maintained by the
Register Stack Engine (RSE).
maxrsessiz
determines the size of this stack.
Who is Expected to Change This Tunable?
Anyone.
Restrictions on Changing
Changes to this tunable only take effect after a reboot of the system.
When Should the Value of This Tunable Be Raised?
maxrsessiz
should be raised if user processes are being terminated with the error
SIGBUS
due to overflow of the RSE stack.
What Are the Side Effects of Raising the Value?
User processes will dedicate more virtual memory to the RSE
stack. This will result in less virtual memory being available for
data allocation.
When Should the Value of This Tunable Be Lowered?
This tunable should be lowered only if swap space is at
a premium on the system, since virtual memory for the RSE stack
still requires matching swap reservation or allocation. Serious
consideration should be given if
maxrsessiz
is being lowered below the default as this may cause unexpected
failures of user applications on RSE stack overflow.
This tunable is best left unchanged without complete and detailed
knowledge of the RSE stack usage of the machine workload.
What Are the Side Effects of Lowering the Value?
Lowering this tunable will limit the amount of memory available for
RSE stack usage per process.
This could cause processes with large RSE stack requirements to terminate
with a
SIGBUS
error.
What Other Tunable Values Should Be Changed at the Same Time?
None.
WARNINGS
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
maxrsessiz
was developed by HP.
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