numa_policy.5 (2010 09)

n
numa_policy(5) numa_policy(5)
(Tunable Kernel Parameters)
Restrictions on Changing
Changes to this tunable take effect on memory allocated subsequent to the change. Any memory created
before the change will not be affected.
When Should the Value of This Tunable Be Changed to 1?
numa_policy should be set to 1 only if all performance-sensitive applications on the system have a high
degree of locality of access. That is, if the majority of references to shared memory are from processes
running on the same cell where the memory has been allocated, then setting
numa_policy = 1 will
have a positive effect on performance. Changing the value to 1 should be done after sufficient memory
has been designated as cell-local using
parmodify(2) and the machine has been rebooted.
When Should the Value of This Tunable Be Changed to 2?
numa_policy can be set to 2 if the workload has a low degree of locality to a cell and it is not possible
to change the source code. Changing the value to 2 should be done after sufficient memory has been
designated as interleaved using parmodify and the machine has been rebooted. Setting the
numa_policy tunable to 2 only makes sense in a mixed environment in which some applications can
benefit from cell-local memory, and others cannot.
When Should the Value of This Tunable Be Changed to 3?
numa_policy can be set to 3 if the all the performance-sensitive applications on the system have a high
degree of locality of access and if the workload is threaded. Changing the value to 3 should be done after
sufficient memory has been designated as cell-local using parmodify and the machine has been
rebooted.
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 parame-
ter 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://www.hp.com/go/hpux-core-docs
.
AUTHOR
numa_policy was developed by HP.
SEE ALSO
chatr_ia(1), mpsched(1), kctune(1M), parmodify(1M), fadvise(2), numa_mode(5), shmget(2).
2 Hewlett-Packard Company 2 HP-UX 11i Version 3: September 2010