From 47c09d6a9f6794caface4ad50930460b82d7c670 Mon Sep 17 00:00:00 2001 From: Song Liu Date: Mon, 9 Mar 2020 10:32:15 -0700 Subject: 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 Signed-off-by: Daniel Borkmann Reviewed-by: Quentin Monnet Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20200309173218.2739965-2-songliubraving@fb.com --- tools/scripts/Makefile.include | 1 + 1 file changed, 1 insertion(+) (limited to 'tools/scripts') diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include index ded7a950dc40..59f31f01cb93 100644 --- a/tools/scripts/Makefile.include +++ b/tools/scripts/Makefile.include @@ -106,6 +106,7 @@ ifneq ($(silent),1) ifneq ($(V),1) QUIET_CC = @echo ' CC '$@; QUIET_CC_FPIC = @echo ' CC FPIC '$@; + QUIET_CLANG = @echo ' CLANG '$@; QUIET_AR = @echo ' AR '$@; QUIET_LINK = @echo ' LINK '$@; QUIET_MKDIR = @echo ' MKDIR '$@; -- cgit v1.2.3