While Simultaneous Multi-Threading (SMT) isn't as common on Arm SoCs as it is in the x86 and POWER worlds, there are some SMT-capable designs like with the HiSilicon Kupeng 930 for Arm servers. HiSilicon engineers are working now to extend Linux's SMT run-time controls to work on ARM64 (AArch64).

Linux on AArch64 to date hasn't supported the run-time SMT controls provided by the kernel's CPU control framework. This allows run-time toggling of SMT if wishing to offline SMT threads as is commonly done on Intel/AMD. HiSilicon is extending the kernel's code now to handle this hot-plug SMT functionality if desired for security vulnerability concerns, better single CPU performance, or trying to reduce system power consumption.

Run-time disabling of SMT on ARM64 will take offline all secondary threads. HiSilicon has successfully tested their ARM64 Linux patch on their SMT-capable ACPI-based ARM64 servers as well as via QEMU VMs.

Those interested in run-time SMT controls for ARM64 platforms can see this kernel patch now under review.