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| author | Song Liu <songliubraving@fb.com> | 2020-03-09 20:32:15 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-03-10 02:04:07 +0300 |
| commit | 47c09d6a9f6794caface4ad50930460b82d7c670 (patch) | |
| tree | bc29e8f83ffc3df13df0650e19c884970a6ab406 /tools/bpf/bpftool/Makefile | |
| parent | 7b4b73bc8a609fa9655022ed24a7a714bc8c2155 (diff) | |
| download | linux-47c09d6a9f6794caface4ad50930460b82d7c670.tar.xz | |
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
Diffstat (limited to 'tools/bpf/bpftool/Makefile')
| -rw-r--r-- | tools/bpf/bpftool/Makefile | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index c4e810335810..20a90d8450f8 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -59,6 +59,7 @@ LIBS = $(LIBBPF) -lelf -lz INSTALL ?= install RM ?= rm -f +CLANG ?= clang FEATURE_USER = .bpftool FEATURE_TESTS = libbfd disassembler-four-args reallocarray zlib @@ -110,6 +111,22 @@ SRCS += $(BFD_SRCS) endif OBJS = $(patsubst %.c,$(OUTPUT)%.o,$(SRCS)) $(OUTPUT)disasm.o +_OBJS = $(filter-out $(OUTPUT)prog.o,$(OBJS)) $(OUTPUT)_prog.o + +$(OUTPUT)_prog.o: prog.c + $(QUIET_CC)$(COMPILE.c) -MMD -DBPFTOOL_WITHOUT_SKELETONS -o $@ $< + +$(OUTPUT)_bpftool: $(_OBJS) $(LIBBPF) + $(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $(_OBJS) $(LIBS) + +skeleton/profiler.bpf.o: skeleton/profiler.bpf.c + $(QUIET_CLANG)$(CLANG) -I$(srctree)/tools/lib -g -O2 -target bpf -c $< -o $@ + +profiler.skel.h: $(OUTPUT)_bpftool skeleton/profiler.bpf.o + $(QUIET_GEN)$(OUTPUT)./_bpftool gen skeleton skeleton/profiler.bpf.o > $@ + +$(OUTPUT)prog.o: prog.c profiler.skel.h + $(QUIET_CC)$(COMPILE.c) -MMD -o $@ $< $(OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c $(QUIET_CC)$(COMPILE.c) -MMD -o $@ $< @@ -125,6 +142,7 @@ $(OUTPUT)%.o: %.c clean: $(LIBBPF)-clean $(call QUIET_CLEAN, bpftool) $(Q)$(RM) -- $(OUTPUT)bpftool $(OUTPUT)*.o $(OUTPUT)*.d + $(Q)$(RM) -- $(OUTPUT)_bpftool profiler.skel.h skeleton/profiler.bpf.o $(Q)$(RM) -r -- $(OUTPUT)libbpf/ $(call QUIET_CLEAN, core-gen) $(Q)$(RM) -- $(OUTPUT)FEATURE-DUMP.bpftool |