Hello, Following two patches address a couple of different issues with Intel C-state package residency counters, which are used to track power saving state usage on Intel chips. The patches don't have any dependencies to each other and can be applied separately. 1) The residency counters are always read from the first CPU of the package via an SMP call, even if they are available from any CPU. This causes extra latency. Patch #1 fixes this issue by flagging the perf event properly and allowing to execute it on any CPU of the package. 2) The residency counters are completely impossible to read from a BPF program running on any other than the first CPU of the package, as the SMP call is not available in this context. Patch #2 addresses this issue by allowing the read of the perf event from the local CPU, similar to what is done in perf_read_event(). This patch also allows reading any other package scope perf events (RAPL/UNCORE) from arbitrary CPUs on a package via BPF. -Tero
