Collecting cgroup statistics is expensive: the existing method is to open and parse a cgroup file for every cgroup of interest. The memory controller already has an efficient alternative through BPF; this series extends that model to the CPU and block I/O controllers.
Patch 1 adds the CPU kfuncs, and patch 2 adds their selftest. Patch 3 adds the blkcg kfuncs, and patch 4 adds their selftest. This v3 combines the two previously posted v2 series: CPU v2: https://lore.kernel.org/all/[email protected]/ blkcg v2: https://lore.kernel.org/all/[email protected]/ === Changes since CPU v2: - Rename bpf_cpu.c to bpf_cgroup.c and use unlikely() and container_of() for the task_group conversion. - Remove bpf_css_flush_rstat() and register the existing css_rstat_flush() in the common kfunc set. - Remove the SLEEPABLE mark bpf_cgroup_base_stat(). Changes since blkcg v2: - Add bpf_cgroup_css() and bpf_css_release() to keep a controller css alive across the sleepable rstat flush. - Add an RCU-protected checked css-to-blkcg conversion and make the blkg iterator take the typed blkcg pointer. - Use the existing css_rstat_flush() and remove bpf_blkcg_flush_stats(). - Do not expose root io.stat values. === Changes since CPU v1: - Make the rstat flush generic, move it to rstat.c, and make it take a css. - Expose cgroup_base_stat directly instead of repacking its CPU times. - Replace the throttled-time aggregation kfunc with a checked RCU cast in the CPU cgroup BPF code. The cast preserves the verifier type needed for the BPF program to perform the per-CPU sum itself. - Remove the scheduler changes. Built with LLVM. Pass test on v7.2-rc5. Ziyang Men (4): cgroup: add BPF kfuncs to read a cpu cgroup's stats selftests/bpf: add cgroup_iter_cpu test for cpu cgroup kfuncs block: add BPF kfuncs to read blkcg io.stat selftests/bpf: add test for blkcg io.stat BPF kfuncs MAINTAINERS | 1 + block/Makefile | 3 + block/bpf_blkcg.c | 138 ++++++++++ kernel/cgroup/Makefile | 2 + kernel/cgroup/bpf_cgroup.c | 100 +++++++ kernel/cgroup/rstat.c | 54 +++- tools/testing/selftests/bpf/cgroup_iter_cpu.h | 22 ++ tools/testing/selftests/bpf/cgroup_iter_io.h | 17 ++ tools/testing/selftests/bpf/config | 4 + .../bpf/prog_tests/cgroup_iter_cpu.c | 259 ++++++++++++++++++ .../selftests/bpf/prog_tests/cgroup_iter_io.c | 254 +++++++++++++++++ .../selftests/bpf/progs/cgroup_iter_cpu.c | 113 ++++++++ .../selftests/bpf/progs/cgroup_iter_io.c | 74 +++++ 13 files changed, 1037 insertions(+), 4 deletions(-) create mode 100644 block/bpf_blkcg.c create mode 100644 kernel/cgroup/bpf_cgroup.c create mode 100644 tools/testing/selftests/bpf/cgroup_iter_cpu.h create mode 100644 tools/testing/selftests/bpf/cgroup_iter_io.h create mode 100644 tools/testing/selftests/bpf/prog_tests/cgroup_iter_cpu.c create mode 100644 tools/testing/selftests/bpf/prog_tests/cgroup_iter_io.c create mode 100644 tools/testing/selftests/bpf/progs/cgroup_iter_cpu.c create mode 100644 tools/testing/selftests/bpf/progs/cgroup_iter_io.c base-commit: 3b5f4b83c4abc0c9b0a7b9e2b44e816611b7f2ec -- 2.53.0-Meta
