Hi Daniel, We are looking at sharing perf events amount multiple processes via pinned perf event array. However, we found this doesn't really work as the perf event is removed from the map when the struct file is released from user space (in perf_event_fd_array_release). This means, the pinned perf event array can be shared among multiple process. But each perf event still has single owner. Once the owner process closes the fd (or terminates), the perf event is removed from the array. I went thought the history of the code and found this behavior is actually expected (commit 3b1efb196eee). In our use case, however, we want to share the perf event among different processes. I think we have a few options to achieve this: 1. Introduce a new flag for the perf event map, like BPF_F_KEEP_PE_OPEN. Once this flag is set, we should not remove the fd on struct file release. Instead, we remove fd in map_release_uref. 2. Allow a different process to hold reference to the perf_event via pinned perf event array. I guess we can achieve this by enabling for BPF_MAP_UPDATE_ELEM perf event array. 3. Other ideas? Could you please let us know your thoughts on this? Thanks, Song
