numa_mode.5 (2010 09)

n
numa_mode(5) numa_mode(5)
(Tunable Kernel Parameters)
NAME
numa_mode - HP-UX kernel mode on NUMA servers
VALUES
Default
0
Allowed values
Integer values 0, -1 or 1
DESCRIPTION
HP-UX can operate in one of two modes (LORA or SMP) when operating on ccNUMA (cache coherent
Non-Uniform Memory Architecture) servers. LORA is the Locality-Optimized Resource Alignment mode.
SMP is the Symmetric Multiprocessor mode. See
lora(7) for information on LORA mode.
LORA mode is optimal when the underlying partition is configured according to the guidelines for LORA
Partitions. In LORA mode, HP-UX attempts to align the allocation of memory and scheduling of processes
within the minimal number of localities. SMP mode is optimal when the partition does not meet the
guidelines for LORA partitions. In SMP mode, HP-UX distributes the memory and CPU allocations across
all the localities.
The
numa_mode tunable allows users to set the mode independent of the partition guidelines.
There are 3 possible values for this tunable.
numa_mode = 0
This value is the default value. HP-UX evaluates the hardware configuration at boot time to
determine the appropriate mode. HP-UX automatically switches into LORA mode when the
partition meets the guidelines for LORA partitions; otherwise, it switches into SMP mode. The
numa_policy(5) tunable should also be set to zero to allow HP-UX to perform memory allo-
cation in NUMA aware manner when HP-UX is set to LORA mode.
Use
sysconf(_SC_LORA_MODE)
to determine the HP-UX mode of operation.
numa_mode = 1
This value causes HP-UX to operate in LORA mode even if the partition does not meet LORA
Partitions guidelines. It minimizes the number of localities used to meet the CPU and memory
requirements of a workload.
numa_mode = -1
This value causes HP-UX to operate in SMP mode operation. It spreads the load evenly across
all the localities.
Restrictions on Changing
Changes to this tunable take effect upon next reboot.
When Should the Value of This Tunable Be Changed to 1?
numa_mode should be changed to 1 if the partition is configured with more than 50% local memory but is
not compliant with LORA guidelines.
When Should the Value of This Tunable Be Changed to -1?
numa_mode should be set to -1 on NUMA server if the partition has been extensively tuned for NUMA
by passing hints to APIs such as fadvise(2), shmget(2), and mpctl(2) or by using commands such as
mpsched(1). The memory allocation policy should be appropriately set using the numa_policy(5) tun-
able.
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.
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1