The perf subsystem is seeing some new feature work landing with the Linux 4.9 development cycle.

Among the perf changes for Linux 4.9 are host tool build fixes when doing cross-builds, support for vendor-supplied JSON files describing PMU events, a new set of tool tips, and initial work on LLVM/Clang support for perf. There is also a variety of fixes and other code improvements too.

More details on the perf changes for Linux 4.9 via this pull request.