Intel Sapphire Rapids CPUs Get RAR Feature To Force TLB Shootdowns

Intel is giving its next generation Xeon processors a feature called Remote Action Requests. This allows the processors to hardware accelerate Translation Lookaside Buffer shootdowns, which should ensure faster calculations in memory.

The new feature will be experimentally put into the new generation of Xeon CPUs, Intel writes on a support page. These are future processors based on the Sapphire Rapids architecture. The feature is called Remote Action Requests or RAR, which can hardware-force TLB shootdowns.

Currently, such shootdowns in the Translation Lookaside Buffer are only done in software, but doing it on the SOC itself could potentially speed up the process, according to an Intel white paper. In a TLB shootdown, a temporarily stored memory address is erased when the read permissions on this part of the memory are restricted, so that other parts of the processor can no longer access it.

The Sapphire Rapids socs are expected to be released in the second quarter of 2022. It is not known whether the RAR feature will also come to any consumer processors with the Sapphire Rapids architecture. According to Intel, the implementation is emphatically an experimental feature and it is not certain that it will also be implemented in future chip architectures. According to the company, that depends on ‘the feedback it gets’ from customers.