Song Liu 47c09d6a9f bpftool: Introduce "prog profile" command ... With fentry/fexit programs, it is possible to profile BPF program with hardware counters. Introduce bpftool "prog profile", which measures key metrics of a BPF program. bpftool prog profile command creates per-cpu perf events. Then it attaches fentry/fexit programs to the target BPF program. The fentry program saves perf event value to a map. The fexit program reads the perf event again, and calculates the difference, which is the instructions/cycles used by the target program. Example input and output: ./bpftool prog profile id 337 duration 3 cycles instructions llc_misses 4228 run_cnt 3403698 cycles (84.08%) 3525294 instructions # 1.04 insn per cycle (84.05%) 13 llc_misses # 3.69 LLC misses per million isns (83.50%) This command measures cycles and instructions for BPF program with id 337 for 3 seconds. The program has triggered 4228 times. The rest of the output is similar to perf-stat. In this example, the counters were only counting ~84% of the time because of time multiplexing of perf counters. Note that, this approach measures cycles and instructions in very small increments. So the fentry/fexit programs introduce noticeable errors to the measurement results. The fentry/fexit programs are generated with BPF skeletons. Therefore, we build bpftool twice. The first time _bpftool is built without skeletons. Then, _bpftool is used to generate the skeletons. The second time, bpftool is built with skeletons. Signed-off-by: Song Liu <songliubraving@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20200309173218.2739965-2-songliubraving@fb.com		2020-03-10 00:04:07 +01:00
..
Makefile.arch	arch: remove tile port	2018-03-16 10:56:03 +01:00
Makefile.include	bpftool: Introduce "prog profile" command	2020-03-10 00:04:07 +01:00
utilities.mak