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BIOS Tuning Options
The BIOS contains many tuning options that change the behavior of CPU, memory,
persistent memory, and NUMA. The location and name may vary between server
platform types, server vendors, persistent memory vendors, or BIOS versions. However,
most applicable tunable options can usually be found in the Advanced menu under
Memory Configuration and Processor Configuration. Refer to your system BIOS user
manual for descriptions of each available option. You may want to test several BIOS
options with the application(s) to understand which options bring the most value.
Automatic NUMA Balancing
Physical limitations to hardware are encountered when many CPUs and a lot of memory
are required. The important limitation is the limited communication bandwidth
between the CPUs and the memory. The NUMA architecture modification addresses
this issue. An application generally performs best when the threads of its processes are
accessing memory on the same NUMA node as the threads are scheduled. Automatic
NUMA balancing moves tasks (which can be threads or processes) closer to the memory
they are accessing. It also moves application data to memory closer to the tasks that
reference it. The kernel does this automatically when automatic NUMA balancing
is active. Most operating systems implement this feature. This section discusses the
feature on Linux; refer to your Linux distribution documentation for specific options as
they may vary.
Automatic NUMA balancing is enabled by default in most Linux distributions and
will automatically activate at boot time when the operating system detects it is running
on hardware with NUMA properties. To determine if the feature is enabled, use the
following command:
$ sudo cat /proc/sys/kernel/numa_balancing
A value of 1 (true) indicates the feature is enabled, whereas a value of 0 (zero/false)
means it is disabled.
Chapter 19 advanCed topiCs
BIOS Tuning Options
The BIOS contains many tuning options that change the behavior of CPU, memory,
persistent memory, and NUMA. The location and name may vary between server
platform types, server vendors, persistent memory vendors, or BIOS versions. However,
most applicable tunable options can usually be found in the Advanced menu under
Memory Configuration and Processor Configuration. Refer to your system BIOS user
manual for descriptions of each available option. You may want to test several BIOS
options with the application(s) to understand which options bring the most value.
Automatic NUMA Balancing
Physical limitations to hardware are encountered when many CPUs and a lot of memory
are required. The important limitation is the limited communication bandwidth
between the CPUs and the memory. The NUMA architecture modification addresses
this issue. An application generally performs best when the threads of its processes are
accessing memory on the same NUMA node as the threads are scheduled. Automatic
NUMA balancing moves tasks (which can be threads or processes) closer to the memory
they are accessing. It also moves application data to memory closer to the tasks that
reference it. The kernel does this automatically when automatic NUMA balancing
is active. Most operating systems implement this feature. This section discusses the
feature on Linux; refer to your Linux distribution documentation for specific options as
they may vary.
Automatic NUMA balancing is enabled by default in most Linux distributions and
will automatically activate at boot time when the operating system detects it is running
on hardware with NUMA properties. To determine if the feature is enabled, use the
following command:
$ sudo cat /proc/sys/kernel/numa_balancing
A value of 1 (true) indicates the feature is enabled, whereas a value of 0 (zero/false)
means it is disabled.
Chapter 19 advanCed topiCs