A set of patches recently posted to the Linux kernel mailing list have now been queued up to a tip/tip.git branch for planned introduction in Linux 7.1. These patches are for enhancing the Linux perf subsystem support for AMD Instruction-Based Sampling (IBS) improvements with next-gen Zen 6 processors.
The AMD IBS improvements for the “future” processors (given the timing, expected to be Zen 6) include:
“Add support for new capabilities that will appear in future AMD CPUs:
– Alternate disable bit with control only MSRs to eliminate the RMW race in existing IBS_{FETCH|OP}_CTL MSRs
– RIP bit 63 filtering, which can be used as hardware assisted privilege filtering, enabling IBS for unprivileged users without
software based privilege filtering
– Fetch latency threshold filter to capture only high-latency fetch events
– Streaming-store filter to sample only instructions that perform streaming stores
– Remote socket indicator for load/store instructions”
The patches confirm AMD IBS introducing support for indicating the data source for remote sockets,, the ability with IBS profiling to optionally only record samples for instructions that do streaming stores, filtering of IBS events based on the RIP bit 63 status, latency filtering only when the value exceeds a programmable threshold, and other improvements.
Basically getting the Linux perf support in order for next-gen Zen 6 processors for those doing instruction-based sampling/profiling, which will be especially useful with the EPYC Venice processors.
These patches are now in tip/tip.git’s perf/core Git branch and thus expected to be submitted for the Linux 7.1 merge window in April.
