3

Is NUMA balancer enabled by default in recent Linux versions? If so how can I disable the NUMA balancer please let me know.

slm
  • 15,396
  • 12
  • 109
  • 124
Pradeep Jagadeesh
  • 85
  • 1
  • 2
  • 10

2 Answers2

8

The automatic NUMA balancing can be disabled by passing the numa_balancing=disable parameter to the kernel. The exact way of doing so depends on the boot loader in use. The same parameter could be controlled via the kernel.numa_balancing sysctl:

echo 0 > /proc/sys/kernel/numa_balancing

or

sysctl -w kernel.numa_balancing=0

It could also be set in /etc/sysctl.conf on distributions that process that file.

Hristo Iliev
  • 72,659
  • 12
  • 135
  • 186
1

This depends on which distribution you are on and the underlying hardware. NUMA should be enabled in the BIOS. To check if NUMA is disabled on your linux use:

`grep -i numa /var/log/dmesg`

this returns No NUMA configuration found, when NUMA enabled, dmesg does not show any information of NUMA initialization.

If NUMA is enabled in BIOS, then execute the command numactl --hardware to list the available nodes on the system.

Note, you can also set numa=off to disable in grub.conf, but its best to change it using BIOS settings.

askb
  • 6,501
  • 30
  • 43
  • Thanks for reply, I want to NUMA to be enabled in a system. But there is something called NUMA balancer inside the Linux OS, its a daemon if I am not wrong, which will automatically optimize the scheduling on the fly. I just want to know how can I disable it, to avoid the automatic balancing. – Pradeep Jagadeesh Dec 03 '14 at 09:32
  • We can disable the numa balancer using echo 0 > /proc/sys/kernel/numa_balancing – Pradeep Jagadeesh Dec 04 '14 at 10:24
  • 1
    Yes, but setting "numa=off" in grub.conf more persistent across reboots. – askb Dec 04 '14 at 11:50