Arm Working On "TLBID" For Linux To Increase Performance On High Core Count CPUs

Arm sent out an initial set of patches this week working on support in the Linux kernel for TLBI Domains. This "TLBID" feature is an upcoming Arm architecture capability designed to increase performance on high core count systems. With TLBID there is the ability to perform Translation Lookaside Buffer (TLB) invalidation on just a subset of the CPU cores rather than always performing TLB invalidation system-wide. They are working on plumbing the Linux kernel support so TLBI commands are sent only to the CPUs where a given process was running to avoid the overhead of clearing the TLB for the entire system. This will be particularly beneficial for high core count Arm server processors. No performance numbers were shared and with this TLBID not yet part of the Arm Architecture Reference Manual, it will likely be some time before seeing it in silicon. Besides the Linux kernel patches, the ARM64 TLBID support also depends upon LLVM 23 and newer or GNU Binutils 2.46 and newer for the necessary instruction support. Those interested in this TLBID work for future Arm processor designs can be found via the Linux kernel mailing list.