AMD Publishes Platform QoS Patches For Next-Gen Processors

Written by Michael Larabel in AMD on 24 September 2018 at 07:03 PM EDT. 11 Comments
This afternoon AMD sent out their first Linux kernel patches for what might end up being a new feature for the "EPYC 2" / Zen 2 processors.

Hitting the Linux kernel mailing list a few minutes ago was a set of experimental / request-for-comments patches on "AMD QoS support".
This series adds support for AMD64 architectural extensions for Platform Quality of Service. These extensions are intended to provide for the monitoring of the usage of certain system resources by one or more processors and for the separate allocation and enforcement of limits on the use of certain system resources by one or more processors.

The monitoring and enforcement are not necessarily applied across the entire system, but in general apply to a QOS domain which corresponds to some shared system resource.

The initial QoS functionality is for L3 cache allocation enforcement, L3 cache occupancy monitoring, L3 code-data prioritization, and memory bandwidth enforcement/allocation. This AMD QoS sounds like -- and implied as much by the Linux code -- akin to Intel RDT (Resource Director Technology).

The AMD Linux developer notes did say that this QoS functionality is for their "next generation of processors." That would be Zen 2 or more specifically likely reserved just for the "EPYC 2" server processors as I doubt we'll end up seeing this QoS functionality enabled for desktop Ryzen CPUs.

The initial patches for this support can be found on the kernel mailing list. In my close monitoring of the Linux kernel mailing list and my various automated detectors to note potentially interesting patches/commits, I believe this is the first of seeing any what is likely next-gen EPYC patches for the Linux kernel... It will certainly be interesting to see what else is on approach for the kernel in the near future as AMD gears up for a very interesting 2019.
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