perf tools: Sync addition of PERF_MEM_SNOOPX_PEER

Add a flag to the 'perf mem' data struct to signal that a request caused a cache-to-cache transfer of a line from a peer of the requestor and wasn't sourced from a lower cache level. The line being moved from one peer cache to another has latency and performance implications. On Arm64 Neoverse systems the data source can indicate a cache-to-cache transfer but not if the line is dirty or clean, so instead of overloading HITM define a new flag that indicates this type of transfer. Committer notes: This really is not syncing with the kernel since the patch to the kernel wasn't merged. But we're going ahead of this as it seems trivial and is just a matter of the perf kernel maintainers to give their ack or for us to find another way of expressing this in the perf records synthesized in userspace from the ARM64 hardware traces.

ASAli Saidi committed 4 years ago