AMD Platform QoS Support For Next-Gen EPYC Processors Landing In Linux 4.21

The AMD Platform QoS support talked about a few months ago on Phoronix is landing for the upcoming Linux 4.21 kernel. While not officially confirmed, this Quality of Service system resource work appears almost surely for the next-generation 7nm EPYC processors coming out in the months ahead.

The AMD QoS platform support is for monitoring the usage of different system resources as well as for allowing limits to be placed on these different resources. Among the initial functionality exposed is around L3 cache monitoring and limiting, L3 data prioritization, and memory bandwidth enforcement.

This AMD QoS code is similar to Intel RDT (Resource Director Technology) and in fact re-uses some of that code within the Linux kernel. AMD previously documented this processor extension here though that technical document now appears to have been removed. Given the timing of these patches, it seems logical this will be supported by the upcoming 2019 EPYC processors.

With re-using the common bits of the Intel RDT code, Intel's INTEL_RDT Kconfig switch for this functionality has been renamed to "RESCTRL" for controlling whether both Intel RDT and AMD Platform QoS support is built into the kernel.

This Platform QoS code has been called for pulling into the upcoming Linux 4.21 merge window via the x86/cache pull request.