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| author | Song Liu <songliubraving@fb.com> | 2020-03-09 10:32:15 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2020-03-10 00:04:07 +0100 |
| commit | 47c09d6a9f6794caface4ad50930460b82d7c670 (patch) | |
| tree | bc29e8f83ffc3df13df0650e19c884970a6ab406 /tools/scripts | |
| parent | 7b4b73bc8a609fa9655022ed24a7a714bc8c2155 (diff) | |
| download | linux-next-47c09d6a9f6794caface4ad50930460b82d7c670.tar.gz | |
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/scripts')
| -rw-r--r-- | tools/scripts/Makefile.include | 1 |
1 files changed, 1 insertions, 0 deletions
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 '$@; QUIET_MKDIR = @echo ' MKDIR '$@; |