Hello everyone, We have prepared patches to address an issue from a previous discussion. The previous discussion email thread is here: https://lore.kernel.org/all/CAADnVQLBt0snxv4bKwg1WKQ9wDFbaDCtZ03v1-LjOTYtsKPckQ@xxxxxxxxxxxxxx/ This patch series adds a new field "used_entries" to struct bpf_map_info and keeps tracking the "count" field in bpf_htab in both the preallocated and non-preallocated cases. bpftool is modified to report the newly added "used_entries" field in struct bpf_map_info and to mark pre-allocated htab maps with "*". These make it easier to view the current memory situation of a hashmap. We have added a new interface function map_get_used_elem in bpf_map_ops to provide an abstraction layer so that other map type implementations can support the "used_entries" attribute in a future change. A concurrency testing for pre-allocated and dynamically allocated htab maps is introduced to test the correctness and performance of htab map's used size. Existing unit tests are integrated to test the correctness of htab map's used size. Thank you, Ho-Ren (Jack) Chuang (4): bpf: Support reporting BPF htab map's used size for monitoring bpftool: Add tools support to show BPF htab map's used size samples/bpf: Add concurrency testing for BPF htab map's used size selftests/bpf: Add unit tests for BPF htab map's used size include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 1 + kernel/bpf/hashtab.c | 19 +++ kernel/bpf/syscall.c | 2 + samples/bpf/Makefile | 4 + samples/bpf/test_map_used_kern.c | 65 ++++++++ samples/bpf/test_map_used_user.c | 204 ++++++++++++++++++++++++ tools/bpf/bpftool/map.c | 9 +- tools/include/uapi/linux/bpf.h | 1 + tools/testing/selftests/bpf/test_maps.c | 74 ++++++++- 10 files changed, 377 insertions(+), 3 deletions(-) create mode 100644 samples/bpf/test_map_used_kern.c create mode 100644 samples/bpf/test_map_used_user.c -- Ho-Ren (Jack) Chuang
