Existing kprobe/fentry triggering benchmarks have 1-to-1 mapping between
one syscall execution and BPF program run. While we use a fast
get_pgid() syscall, syscall overhead can still be non-trivial.
This patch adds kprobe/fentry set of benchmarks significantly amortizing
the cost of syscall vs actual BPF triggering overhead. We do this by
employing BPF_PROG_TEST_RUN command to trigger "driver" raw_tp program
which does a tight parameterized loop calling cheap BPF helper
(bpf_get_numa_node_id()), to which kprobe/fentry programs are
attached for benchmarking.
This way 1 bpf() syscall causes N executions of BPF program being
benchmarked. N defaults to 100, but can be adjusted with
--trig-batch-iters CLI argument.
For comparison we also implement a new baseline program that instead of
triggering another BPF program just does N atomic per-CPU counter
increments, establishing the limit for all other types of program within
this batched benchmarking setup.
Taking the final set of benchmarks added in this patch set (including
tp/raw_tp/fmodret, added in later patch), and keeping for now "legacy"
syscall-driven benchmarks, we can capture all triggering benchmarks in
one place for comparison, before we remove the legacy ones (and rename
xxx-batched into just xxx).
$ benchs/run_bench_trigger.sh
usermode-count : 79.500 ± 0.024M/s
kernel-count : 49.949 ± 0.081M/s
syscall-count : 9.009 ± 0.007M/s
fentry-batch : 31.002 ± 0.015M/s
fexit-batch : 20.372 ± 0.028M/s
fmodret-batch : 21.651 ± 0.659M/s
rawtp-batch : 36.775 ± 0.264M/s
tp-batch : 19.411 ± 0.248M/s
kprobe-batch : 12.949 ± 0.220M/s
kprobe-multi-batch : 15.400 ± 0.007M/s
kretprobe-batch : 5.559 ± 0.011M/s
kretprobe-multi-batch: 5.861 ± 0.003M/s
fentry-legacy : 8.329 ± 0.004M/s
fexit-legacy : 6.239 ± 0.003M/s
fmodret-legacy : 6.595 ± 0.001M/s
rawtp-legacy : 8.305 ± 0.004M/s
tp-legacy : 6.382 ± 0.001M/s
kprobe-legacy : 5.528 ± 0.003M/s
kprobe-multi-legacy : 5.864 ± 0.022M/s
kretprobe-legacy : 3.081 ± 0.001M/s
kretprobe-multi-legacy: 3.193 ± 0.001M/s
Note how xxx-batch variants are measured with significantly higher
throughput, even though it's exactly the same in-kernel overhead. As
such, results can be compared only between benchmarks of the same kind
(syscall vs batched):
fentry-legacy : 8.329 ± 0.004M/s
fentry-batch : 31.002 ± 0.015M/s
kprobe-multi-legacy : 5.864 ± 0.022M/s
kprobe-multi-batch : 15.400 ± 0.007M/s
Note also that syscall-count is setting a theoretical limit for
syscall-triggered benchmarks, while kernel-count is setting similar
limits for batch variants. usermode-count is a happy and unachievable
case of user space counting without doing any syscalls, and is mostly
the measure of CPU speed for such a trivial benchmark.
As was mentioned, tp/raw_tp/fmodret require kernel-side kfunc to produce
similar benchmark, which we address in a separate patch.
Note that run_bench_trigger.sh allows to override a list of benchmarks
to run, which is very useful for performance work.
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
tools/testing/selftests/bpf/bench.c | 21 ++-
.../selftests/bpf/benchs/bench_trigger.c | 133 +++++++++++++++++-
.../selftests/bpf/benchs/run_bench_trigger.sh | 24 +++-
.../selftests/bpf/progs/trigger_bench.c | 67 ++++++++-
4 files changed, 238 insertions(+), 7 deletions(-)
diff --git a/tools/testing/selftests/bpf/bench.c b/tools/testing/selftests/bpf/bench.c
index 7ca1e1eb5c30..484bcbeaa819 100644
--- a/tools/testing/selftests/bpf/bench.c
+++ b/tools/testing/selftests/bpf/bench.c
@@ -280,6 +280,7 @@ extern struct argp bench_strncmp_argp;
extern struct argp bench_hashmap_lookup_argp;
extern struct argp bench_local_storage_create_argp;
extern struct argp bench_htab_mem_argp;
+extern struct argp bench_trigger_batch_argp;
static const struct argp_child bench_parsers[] = {
{ &bench_ringbufs_argp, 0, "Ring buffers benchmark", 0 },
@@ -292,6 +293,7 @@ static const struct argp_child bench_parsers[] = {
{ &bench_hashmap_lookup_argp, 0, "Hashmap lookup benchmark", 0 },
{ &bench_local_storage_create_argp, 0, "local-storage-create benchmark", 0 },
{ &bench_htab_mem_argp, 0, "hash map memory benchmark", 0 },
+ { &bench_trigger_batch_argp, 0, "BPF triggering benchmark", 0 },
{},
};
@@ -508,6 +510,15 @@ extern const struct bench bench_trig_fexit;
extern const struct bench bench_trig_fentry_sleep;
extern const struct bench bench_trig_fmodret;
+/* batched, staying mostly in-kernel benchmarks */
+extern const struct bench bench_trig_kernel_count;
+extern const struct bench bench_trig_kprobe_batch;
+extern const struct bench bench_trig_kretprobe_batch;
+extern const struct bench bench_trig_kprobe_multi_batch;
+extern const struct bench bench_trig_kretprobe_multi_batch;
+extern const struct bench bench_trig_fentry_batch;
+extern const struct bench bench_trig_fexit_batch;
+
/* uprobe/uretprobe benchmarks */
extern const struct bench bench_trig_uprobe_nop;
extern const struct bench bench_trig_uretprobe_nop;
@@ -548,7 +559,7 @@ static const struct bench *benchs[] = {
&bench_rename_fexit,
/* pure counting benchmarks for establishing theoretical limits */
&bench_trig_usermode_count,
- &bench_trig_base,
+ &bench_trig_kernel_count,
/* syscall-driven triggering benchmarks */
&bench_trig_tp,
&bench_trig_rawtp,
@@ -560,6 +571,13 @@ static const struct bench *benchs[] = {
&bench_trig_fexit,
&bench_trig_fentry_sleep,
&bench_trig_fmodret,
+ /* batched, staying mostly in-kernel triggers */
+ &bench_trig_kprobe_batch,
+ &bench_trig_kretprobe_batch,
+ &bench_trig_kprobe_multi_batch,
+ &bench_trig_kretprobe_multi_batch,
+ &bench_trig_fentry_batch,
+ &bench_trig_fexit_batch,
/* uprobes */
&bench_trig_uprobe_nop,
&bench_trig_uretprobe_nop,
@@ -567,6 +585,7 @@ static const struct bench *benchs[] = {
&bench_trig_uretprobe_push,
&bench_trig_uprobe_ret,
&bench_trig_uretprobe_ret,
+ /* ringbuf/perfbuf benchmarks */
&bench_rb_libbpf,
&bench_rb_custom,
&bench_pb_libbpf,
diff --git a/tools/testing/selftests/bpf/benchs/bench_trigger.c b/tools/testing/selftests/bpf/benchs/bench_trigger.c
index 97aba7e6458d..20277dabdaf9 100644
--- a/tools/testing/selftests/bpf/benchs/bench_trigger.c
+++ b/tools/testing/selftests/bpf/benchs/bench_trigger.c
@@ -1,11 +1,57 @@
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020 Facebook */
#define _GNU_SOURCE
+#include <argp.h>
#include <unistd.h>
+#include <stdint.h>
#include "bench.h"
#include "trigger_bench.skel.h"
#include "trace_helpers.h"
+#define MAX_TRIG_BATCH_ITERS 1000
+
+static struct {
+ __u32 batch_iters;
+} args = {
+ .batch_iters = 100,
+};
+
+enum {
+ ARG_TRIG_BATCH_ITERS = 7000,
+};
+
+static const struct argp_option opts[] = {
+ { "trig-batch-iters", ARG_TRIG_BATCH_ITERS, "BATCH_ITER_CNT", 0,
+ "Number of in-kernel iterations per one driver test run"},
+ {},
+};
+
+static error_t parse_arg(int key, char *arg, struct argp_state *state)
+{
+ long ret;
+
+ switch (key) {
+ case ARG_TRIG_BATCH_ITERS:
+ ret = strtol(arg, NULL, 10);
+ if (ret < 1 || ret > MAX_TRIG_BATCH_ITERS) {
+ fprintf(stderr, "invalid --trig-batch-iters value (should be between %d and %d)\n",
+ 1, MAX_TRIG_BATCH_ITERS);
+ argp_usage(state);
+ }
+ args.batch_iters = ret;
+ break;
+ default:
+ return ARGP_ERR_UNKNOWN;
+ }
+
+ return 0;
+}
+
+const struct argp bench_trigger_batch_argp = {
+ .options = opts,
+ .parser = parse_arg,
+};
+
/* adjust slot shift in inc_hits() if changing */
#define MAX_BUCKETS 256
@@ -15,6 +61,7 @@
static struct trigger_ctx {
struct trigger_bench *skel;
bool usermode_counters;
+ int driver_prog_fd;
} ctx;
static struct counter base_hits[MAX_BUCKETS];
@@ -73,6 +120,16 @@ static void *trigger_producer(void *input)
return NULL;
}
+static void *trigger_producer_batch(void *input)
+{
+ int fd = ctx.driver_prog_fd ?: bpf_program__fd(ctx.skel->progs.trigger_driver);
+
+ while (true)
+ bpf_prog_test_run_opts(fd, NULL);
+
+ return NULL;
+}
+
static void trigger_measure(struct bench_res *res)
{
if (ctx.usermode_counters)
@@ -83,13 +140,23 @@ static void trigger_measure(struct bench_res *res)
static void setup_ctx(void)
{
+ int err;
+
setup_libbpf();
- ctx.skel = trigger_bench__open_and_load();
+ ctx.skel = trigger_bench__open();
if (!ctx.skel) {
fprintf(stderr, "failed to open skeleton\n");
exit(1);
}
+
+ ctx.skel->rodata->batch_iters = args.batch_iters;
+
+ err = trigger_bench__load(ctx.skel);
+ if (err) {
+ fprintf(stderr, "failed to open skeleton\n");
+ exit(1);
+ }
}
static void attach_bpf(struct bpf_program *prog)
@@ -163,6 +230,50 @@ static void trigger_fmodret_setup(void)
attach_bpf(ctx.skel->progs.bench_trigger_fmodret);
}
+/* Batched, staying mostly in-kernel triggering setups */
+static void trigger_kernel_count_setup(void)
+{
+ setup_ctx();
+ /* override driver program */
+ ctx.driver_prog_fd = bpf_program__fd(ctx.skel->progs.trigger_count);
+}
+
+static void trigger_kprobe_batch_setup(void)
+{
+ setup_ctx();
+ attach_bpf(ctx.skel->progs.bench_trigger_kprobe_batch);
+}
+
+static void trigger_kretprobe_batch_setup(void)
+{
+ setup_ctx();
+ attach_bpf(ctx.skel->progs.bench_trigger_kretprobe_batch);
+}
+
+static void trigger_kprobe_multi_batch_setup(void)
+{
+ setup_ctx();
+ attach_bpf(ctx.skel->progs.bench_trigger_kprobe_multi_batch);
+}
+
+static void trigger_kretprobe_multi_batch_setup(void)
+{
+ setup_ctx();
+ attach_bpf(ctx.skel->progs.bench_trigger_kretprobe_multi_batch);
+}
+
+static void trigger_fentry_batch_setup(void)
+{
+ setup_ctx();
+ attach_bpf(ctx.skel->progs.bench_trigger_fentry_batch);
+}
+
+static void trigger_fexit_batch_setup(void)
+{
+ setup_ctx();
+ attach_bpf(ctx.skel->progs.bench_trigger_fexit_batch);
+}
+
/* make sure call is not inlined and not avoided by compiler, so __weak and
* inline asm volatile in the body of the function
*
@@ -396,6 +507,26 @@ const struct bench bench_trig_fmodret = {
.report_final = hits_drops_report_final,
};
+/* batched (staying mostly in kernel) kprobe/fentry benchmarks */
+#define BENCH_TRIG_BATCH(KIND, NAME) \
+const struct bench bench_trig_##KIND = { \
+ .name = "trig-" NAME, \
+ .setup = trigger_##KIND##_setup, \
+ .producer_thread = trigger_producer_batch, \
+ .measure = trigger_measure, \
+ .report_progress = hits_drops_report_progress, \
+ .report_final = hits_drops_report_final, \
+ .argp = &bench_trigger_batch_argp, \
+}
+
+BENCH_TRIG_BATCH(kernel_count, "kernel-count");
+BENCH_TRIG_BATCH(kprobe_batch, "kprobe-batch");
+BENCH_TRIG_BATCH(kretprobe_batch, "kretprobe-batch");
+BENCH_TRIG_BATCH(kprobe_multi_batch, "kprobe-multi-batch");
+BENCH_TRIG_BATCH(kretprobe_multi_batch, "kretprobe-multi-batch");
+BENCH_TRIG_BATCH(fentry_batch, "fentry-batch");
+BENCH_TRIG_BATCH(fexit_batch, "fexit-batch");
+
/* uprobe benchmarks */
#define BENCH_TRIG_USERMODE(KIND, PRODUCER, NAME) \
const struct bench bench_trig_##KIND = { \
diff --git a/tools/testing/selftests/bpf/benchs/run_bench_trigger.sh b/tools/testing/selftests/bpf/benchs/run_bench_trigger.sh
index 78e83f243294..b58ec33ea18c 100755
--- a/tools/testing/selftests/bpf/benchs/run_bench_trigger.sh
+++ b/tools/testing/selftests/bpf/benchs/run_bench_trigger.sh
@@ -2,8 +2,24 @@
set -eufo pipefail
-for i in base tp rawtp kprobe fentry fmodret
-do
- summary=$(sudo ./bench -w2 -d5 -a trig-$i | tail -n1 | cut -d'(' -f1 | cut -d' ' -f3-)
- printf "%-10s: %s\n" $i "$summary"
+def_tests=( \
+ usermode-count kernel-count syscall-count \
+ fentry-batch fexit-batch \
+ kprobe-batch kprobe-multi-batch \
+ kretprobe-batch kretprobe-multi-batch \
+ fentry fexit fmodret \
+ rawtp tp \
+ kprobe kprobe-multi kretprobe kretprobe-multi \
+)
+
+tests=("$@")
+if [ ${#tests[@]} -eq 0 ]; then
+ tests=("${def_tests[@]}")
+fi
+
+p=${PROD_CNT:-1}
+
+for t in "${tests[@]}"; do
+ summary=$(sudo ./bench -w2 -d5 -a -p$p trig-$t | tail -n1 | cut -d'(' -f1 | cut -d' ' -f3-)
+ printf "%-21s: %s\n" $t "$summary"
done
diff --git a/tools/testing/selftests/bpf/progs/trigger_bench.c b/tools/testing/selftests/bpf/progs/trigger_bench.c
index 42ec202015ed..f0b76afa5017 100644
--- a/tools/testing/selftests/bpf/progs/trigger_bench.c
+++ b/tools/testing/selftests/bpf/progs/trigger_bench.c
@@ -1,6 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2020 Facebook
-
#include <linux/bpf.h>
#include <asm/unistd.h>
#include <bpf/bpf_helpers.h>
@@ -103,3 +102,69 @@ int bench_trigger_uprobe(void *ctx)
inc_counter();
return 0;
}
+
+const volatile int batch_iters = 0;
+
+SEC("raw_tp")
+int trigger_count(void *ctx)
+{
+ int i;
+
+ for (i = 0; i < batch_iters; i++)
+ inc_counter();
+
+ return 0;
+}
+
+SEC("raw_tp")
+int trigger_driver(void *ctx)
+{
+ int i;
+
+ for (i = 0; i < batch_iters; i++)
+ (void)bpf_get_numa_node_id(); /* attach point for benchmarking */
+
+ return 0;
+}
+
+SEC("kprobe/bpf_get_numa_node_id")
+int bench_trigger_kprobe_batch(void *ctx)
+{
+ inc_counter();
+ return 0;
+}
+
+SEC("kretprobe/bpf_get_numa_node_id")
+int bench_trigger_kretprobe_batch(void *ctx)
+{
+ inc_counter();
+ return 0;
+}
+
+SEC("kprobe.multi/bpf_get_numa_node_id")
+int bench_trigger_kprobe_multi_batch(void *ctx)
+{
+ inc_counter();
+ return 0;
+}
+
+SEC("kretprobe.multi/bpf_get_numa_node_id")
+int bench_trigger_kretprobe_multi_batch(void *ctx)
+{
+ inc_counter();
+ return 0;
+}
+
+SEC("fentry/bpf_get_numa_node_id")
+int bench_trigger_fentry_batch(void *ctx)
+{
+ inc_counter();
+ return 0;
+}
+
+SEC("fexit/bpf_get_numa_node_id")
+int bench_trigger_fexit_batch(void *ctx)
+{
+ inc_counter();
+ return 0;
+}
--
2.43.0
