selftest/bpf: Fmod_ret prog and implement test_overhead as part of bench
authorAndrii Nakryiko <andriin@fb.com>
Tue, 12 May 2020 19:24:44 +0000 (12:24 -0700)
committerAlexei Starovoitov <ast@kernel.org>
Wed, 13 May 2020 19:19:38 +0000 (12:19 -0700)
Add fmod_ret BPF program to existing test_overhead selftest. Also re-implement
user-space benchmarking part into benchmark runner to compare results. Results
with ./bench are consistently somewhat lower than test_overhead's, but relative
performance of various types of BPF programs stay consisten (e.g., kretprobe is
noticeably slower). This slowdown seems to be coming from the fact that
test_overhead is single-threaded, while benchmark always spins off at least
one thread for producer. This has been confirmed by hacking multi-threaded
test_overhead variant and also single-threaded bench variant. Resutls are
below. run_bench_rename.sh script from benchs/ subdirectory was used to
produce results for ./bench.

Single-threaded implementations
===============================

/* bench: single-threaded, atomics */
base      :    4.622 ± 0.049M/s
kprobe    :    3.673 ± 0.052M/s
kretprobe :    2.625 ± 0.052M/s
rawtp     :    4.369 ± 0.089M/s
fentry    :    4.201 ± 0.558M/s
fexit     :    4.309 ± 0.148M/s
fmodret   :    4.314 ± 0.203M/s

/* selftest: single-threaded, no atomics */
task_rename base        4555K events per sec
task_rename kprobe      3643K events per sec
task_rename kretprobe   2506K events per sec
task_rename raw_tp      4303K events per sec
task_rename fentry      4307K events per sec
task_rename fexit       4010K events per sec
task_rename fmod_ret    3984K events per sec

Multi-threaded implementations
==============================

/* bench: multi-threaded w/ atomics */
base      :    3.910 ± 0.023M/s
kprobe    :    3.048 ± 0.037M/s
kretprobe :    2.300 ± 0.015M/s
rawtp     :    3.687 ± 0.034M/s
fentry    :    3.740 ± 0.087M/s
fexit     :    3.510 ± 0.009M/s
fmodret   :    3.485 ± 0.050M/s

/* selftest: multi-threaded w/ atomics */
task_rename base        3872K events per sec
task_rename kprobe      3068K events per sec
task_rename kretprobe   2350K events per sec
task_rename raw_tp      3731K events per sec
task_rename fentry      3639K events per sec
task_rename fexit       3558K events per sec
task_rename fmod_ret    3511K events per sec

/* selftest: multi-threaded, no atomics */
task_rename base        3945K events per sec
task_rename kprobe      3298K events per sec
task_rename kretprobe   2451K events per sec
task_rename raw_tp      3718K events per sec
task_rename fentry      3782K events per sec
task_rename fexit       3543K events per sec
task_rename fmod_ret    3526K events per sec

Note that the fact that ./bench benchmark always uses atomic increments for
counting, while test_overhead doesn't, doesn't influence test results all that
much.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200512192445.2351848-4-andriin@fb.com
tools/testing/selftests/bpf/Makefile
tools/testing/selftests/bpf/bench.c
tools/testing/selftests/bpf/benchs/bench_rename.c [new file with mode: 0644]
tools/testing/selftests/bpf/benchs/run_bench_rename.sh [new file with mode: 0755]
tools/testing/selftests/bpf/prog_tests/test_overhead.c
tools/testing/selftests/bpf/progs/test_overhead.c

index f414b24..1a079e9 100644 (file)
@@ -411,10 +411,12 @@ $(OUTPUT)/test_cpp: test_cpp.cpp $(OUTPUT)/test_core_extern.skel.h $(BPFOBJ)
 $(OUTPUT)/bench_%.o: benchs/bench_%.c bench.h
        $(call msg,CC,,$@)
        $(CC) $(CFLAGS) -c $(filter %.c,$^) $(LDLIBS) -o $@
+$(OUTPUT)/bench_rename.o: $(OUTPUT)/test_overhead.skel.h
 $(OUTPUT)/bench.o: bench.h testing_helpers.h
 $(OUTPUT)/bench: LDLIBS += -lm
 $(OUTPUT)/bench: $(OUTPUT)/bench.o $(OUTPUT)/testing_helpers.o \
-                $(OUTPUT)/bench_count.o
+                $(OUTPUT)/bench_count.o \
+                $(OUTPUT)/bench_rename.o
        $(call msg,BINARY,,$@)
        $(CC) $(LDFLAGS) -o $@ $(filter %.a %.o,$^) $(LDLIBS)
 
index 3972da8..c9e8b7d 100644 (file)
@@ -297,10 +297,24 @@ const struct bench *bench = NULL;
 
 extern const struct bench bench_count_global;
 extern const struct bench bench_count_local;
+extern const struct bench bench_rename_base;
+extern const struct bench bench_rename_kprobe;
+extern const struct bench bench_rename_kretprobe;
+extern const struct bench bench_rename_rawtp;
+extern const struct bench bench_rename_fentry;
+extern const struct bench bench_rename_fexit;
+extern const struct bench bench_rename_fmodret;
 
 static const struct bench *benchs[] = {
        &bench_count_global,
        &bench_count_local,
+       &bench_rename_base,
+       &bench_rename_kprobe,
+       &bench_rename_kretprobe,
+       &bench_rename_rawtp,
+       &bench_rename_fentry,
+       &bench_rename_fexit,
+       &bench_rename_fmodret,
 };
 
 static void setup_benchmark()
diff --git a/tools/testing/selftests/bpf/benchs/bench_rename.c b/tools/testing/selftests/bpf/benchs/bench_rename.c
new file mode 100644 (file)
index 0000000..e74cff4
--- /dev/null
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include <fcntl.h>
+#include "bench.h"
+#include "test_overhead.skel.h"
+
+/* BPF triggering benchmarks */
+static struct ctx {
+       struct test_overhead *skel;
+       struct counter hits;
+       int fd;
+} ctx;
+
+static void validate()
+{
+       if (env.producer_cnt != 1) {
+               fprintf(stderr, "benchmark doesn't support multi-producer!\n");
+               exit(1);
+       }
+       if (env.consumer_cnt != 1) {
+               fprintf(stderr, "benchmark doesn't support multi-consumer!\n");
+               exit(1);
+       }
+}
+
+static void *producer(void *input)
+{
+       char buf[] = "test_overhead";
+       int err;
+
+       while (true) {
+               err = write(ctx.fd, buf, sizeof(buf));
+               if (err < 0) {
+                       fprintf(stderr, "write failed\n");
+                       exit(1);
+               }
+               atomic_inc(&ctx.hits.value);
+       }
+}
+
+static void measure(struct bench_res *res)
+{
+       res->hits = atomic_swap(&ctx.hits.value, 0);
+}
+
+static void setup_ctx()
+{
+       setup_libbpf();
+
+       ctx.skel = test_overhead__open_and_load();
+       if (!ctx.skel) {
+               fprintf(stderr, "failed to open skeleton\n");
+               exit(1);
+       }
+
+       ctx.fd = open("/proc/self/comm", O_WRONLY|O_TRUNC);
+       if (ctx.fd < 0) {
+               fprintf(stderr, "failed to open /proc/self/comm: %d\n", -errno);
+               exit(1);
+       }
+}
+
+static void attach_bpf(struct bpf_program *prog)
+{
+       struct bpf_link *link;
+
+       link = bpf_program__attach(prog);
+       if (IS_ERR(link)) {
+               fprintf(stderr, "failed to attach program!\n");
+               exit(1);
+       }
+}
+
+static void setup_base()
+{
+       setup_ctx();
+}
+
+static void setup_kprobe()
+{
+       setup_ctx();
+       attach_bpf(ctx.skel->progs.prog1);
+}
+
+static void setup_kretprobe()
+{
+       setup_ctx();
+       attach_bpf(ctx.skel->progs.prog2);
+}
+
+static void setup_rawtp()
+{
+       setup_ctx();
+       attach_bpf(ctx.skel->progs.prog3);
+}
+
+static void setup_fentry()
+{
+       setup_ctx();
+       attach_bpf(ctx.skel->progs.prog4);
+}
+
+static void setup_fexit()
+{
+       setup_ctx();
+       attach_bpf(ctx.skel->progs.prog5);
+}
+
+static void setup_fmodret()
+{
+       setup_ctx();
+       attach_bpf(ctx.skel->progs.prog6);
+}
+
+static void *consumer(void *input)
+{
+       return NULL;
+}
+
+const struct bench bench_rename_base = {
+       .name = "rename-base",
+       .validate = validate,
+       .setup = setup_base,
+       .producer_thread = producer,
+       .consumer_thread = consumer,
+       .measure = measure,
+       .report_progress = hits_drops_report_progress,
+       .report_final = hits_drops_report_final,
+};
+
+const struct bench bench_rename_kprobe = {
+       .name = "rename-kprobe",
+       .validate = validate,
+       .setup = setup_kprobe,
+       .producer_thread = producer,
+       .consumer_thread = consumer,
+       .measure = measure,
+       .report_progress = hits_drops_report_progress,
+       .report_final = hits_drops_report_final,
+};
+
+const struct bench bench_rename_kretprobe = {
+       .name = "rename-kretprobe",
+       .validate = validate,
+       .setup = setup_kretprobe,
+       .producer_thread = producer,
+       .consumer_thread = consumer,
+       .measure = measure,
+       .report_progress = hits_drops_report_progress,
+       .report_final = hits_drops_report_final,
+};
+
+const struct bench bench_rename_rawtp = {
+       .name = "rename-rawtp",
+       .validate = validate,
+       .setup = setup_rawtp,
+       .producer_thread = producer,
+       .consumer_thread = consumer,
+       .measure = measure,
+       .report_progress = hits_drops_report_progress,
+       .report_final = hits_drops_report_final,
+};
+
+const struct bench bench_rename_fentry = {
+       .name = "rename-fentry",
+       .validate = validate,
+       .setup = setup_fentry,
+       .producer_thread = producer,
+       .consumer_thread = consumer,
+       .measure = measure,
+       .report_progress = hits_drops_report_progress,
+       .report_final = hits_drops_report_final,
+};
+
+const struct bench bench_rename_fexit = {
+       .name = "rename-fexit",
+       .validate = validate,
+       .setup = setup_fexit,
+       .producer_thread = producer,
+       .consumer_thread = consumer,
+       .measure = measure,
+       .report_progress = hits_drops_report_progress,
+       .report_final = hits_drops_report_final,
+};
+
+const struct bench bench_rename_fmodret = {
+       .name = "rename-fmodret",
+       .validate = validate,
+       .setup = setup_fmodret,
+       .producer_thread = producer,
+       .consumer_thread = consumer,
+       .measure = measure,
+       .report_progress = hits_drops_report_progress,
+       .report_final = hits_drops_report_final,
+};
diff --git a/tools/testing/selftests/bpf/benchs/run_bench_rename.sh b/tools/testing/selftests/bpf/benchs/run_bench_rename.sh
new file mode 100755 (executable)
index 0000000..16f774b
--- /dev/null
@@ -0,0 +1,9 @@
+#!/bin/bash
+
+set -eufo pipefail
+
+for i in base kprobe kretprobe rawtp fentry fexit fmodret
+do
+       summary=$(sudo ./bench -w2 -d5 -a rename-$i | tail -n1 | cut -d'(' -f1 | cut -d' ' -f3-)
+       printf "%-10s: %s\n" $i "$summary"
+done
index 465b371..2702df2 100644 (file)
@@ -61,9 +61,10 @@ void test_test_overhead(void)
        const char *raw_tp_name = "raw_tp/task_rename";
        const char *fentry_name = "fentry/__set_task_comm";
        const char *fexit_name = "fexit/__set_task_comm";
+       const char *fmodret_name = "fmod_ret/__set_task_comm";
        const char *kprobe_func = "__set_task_comm";
        struct bpf_program *kprobe_prog, *kretprobe_prog, *raw_tp_prog;
-       struct bpf_program *fentry_prog, *fexit_prog;
+       struct bpf_program *fentry_prog, *fexit_prog, *fmodret_prog;
        struct bpf_object *obj;
        struct bpf_link *link;
        int err, duration = 0;
@@ -96,6 +97,10 @@ void test_test_overhead(void)
        if (CHECK(!fexit_prog, "find_probe",
                  "prog '%s' not found\n", fexit_name))
                goto cleanup;
+       fmodret_prog = bpf_object__find_program_by_title(obj, fmodret_name);
+       if (CHECK(!fmodret_prog, "find_probe",
+                 "prog '%s' not found\n", fmodret_name))
+               goto cleanup;
 
        err = bpf_object__load(obj);
        if (CHECK(err, "obj_load", "err %d\n", err))
@@ -142,6 +147,13 @@ void test_test_overhead(void)
                goto cleanup;
        test_run("fexit");
        bpf_link__destroy(link);
+
+       /* attach fmod_ret */
+       link = bpf_program__attach_trace(fmodret_prog);
+       if (CHECK(IS_ERR(link), "attach fmod_ret", "err %ld\n", PTR_ERR(link)))
+               goto cleanup;
+       test_run("fmod_ret");
+       bpf_link__destroy(link);
 cleanup:
        prctl(PR_SET_NAME, comm, 0L, 0L, 0L);
        bpf_object__close(obj);
index 56a50b2..450bf81 100644 (file)
@@ -39,4 +39,10 @@ int BPF_PROG(prog5, struct task_struct *tsk, const char *buf, bool exec)
        return !tsk;
 }
 
+SEC("fmod_ret/__set_task_comm")
+int BPF_PROG(prog6, struct task_struct *tsk, const char *buf, bool exec)
+{
+       return !tsk;
+}
+
 char _license[] SEC("license") = "GPL";