arm64: add NUMA emulation support

Add NUMA emulation support to emulate NUMA on non-NUMA platforms. A new
CONFIG_NUMA_EMU option enables NUMA emulation and a new kernel command
line option "numa=fake=N" allows users to specify the configuration for

When NUMA emulation is enabled, a flat (non-NUMA) machine will be split
into virtual NUMA nodes when booted with "numa=fake=N", where N is the
number of nodes, the system RAM will be split into N equal chunks and
assigned to each node.

Emulated nodes are bounded by MAX_NUMNODES and the number of memory block
count to avoid splitting memory blocks across NUMA nodes.

If NUMA emulation init fails, it will fall back to dummy NUMA init.

This is tested on Raspberry Pi3b+ with ltp NUMA test suite, numactl, and
numastat tools. In addition, tested in conjunction with cpuset cgroup to
verify cpuset.cpus and cpuset.mems assignments.

Signed-off-by: Shuah Khan (Samsung OSG) <>
Signed-off-by: Shuah Khan <>
5 files changed