Add benchmark to compare the performance between home-made strncmp()
in bpf program and bpf_strncmp() helper. In summary, the performance
win of bpf_strncmp() under x86-64 is greater than 18% when the compared
string length is greater than 64, and is 179% when the length is 4095.
Under arm64 the performance win is even bigger: 33% when the length
is greater than 64 and 600% when the length is 4095.
The following is the details:
no-helper-X: use home-made strncmp() to compare X-sized string
helper-Y: use bpf_strncmp() to compare Y-sized string
Under x86-64:
no-helper-1 3.504 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-1 3.347 ± 0.001M/s (drops 0.000 ± 0.000M/s)
no-helper-8 3.357 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper-8 3.307 ± 0.001M/s (drops 0.000 ± 0.000M/s)
no-helper-32 3.064 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-32 3.253 ± 0.001M/s (drops 0.000 ± 0.000M/s)
no-helper-64 2.563 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper-64 3.040 ± 0.001M/s (drops 0.000 ± 0.000M/s)
no-helper-128 1.975 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-128 2.641 ± 0.000M/s (drops 0.000 ± 0.000M/s)
no-helper-512 0.759 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-512 1.574 ± 0.000M/s (drops 0.000 ± 0.000M/s)
no-helper-2048 0.329 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-2048 0.602 ± 0.000M/s (drops 0.000 ± 0.000M/s)
no-helper-4095 0.117 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-4095 0.327 ± 0.000M/s (drops 0.000 ± 0.000M/s)
Under arm64:
no-helper-1 2.806 ± 0.004M/s (drops 0.000 ± 0.000M/s)
helper-1 2.819 ± 0.002M/s (drops 0.000 ± 0.000M/s)
no-helper-8 2.797 ± 0.109M/s (drops 0.000 ± 0.000M/s)
helper-8 2.786 ± 0.025M/s (drops 0.000 ± 0.000M/s)
no-helper-32 2.399 ± 0.011M/s (drops 0.000 ± 0.000M/s)
helper-32 2.703 ± 0.002M/s (drops 0.000 ± 0.000M/s)
no-helper-64 2.020 ± 0.015M/s (drops 0.000 ± 0.000M/s)
helper-64 2.702 ± 0.073M/s (drops 0.000 ± 0.000M/s)
no-helper-128 1.604 ± 0.001M/s (drops 0.000 ± 0.000M/s)
helper-128 2.516 ± 0.002M/s (drops 0.000 ± 0.000M/s)
no-helper-512 0.699 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-512 2.106 ± 0.003M/s (drops 0.000 ± 0.000M/s)
no-helper-2048 0.215 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-2048 1.223 ± 0.003M/s (drops 0.000 ± 0.000M/s)
no-helper-4095 0.112 ± 0.000M/s (drops 0.000 ± 0.000M/s)
helper-4095 0.796 ± 0.000M/s (drops 0.000 ± 0.000M/s)
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
tools/testing/selftests/bpf/Makefile | 4 +-
tools/testing/selftests/bpf/bench.c | 6 +
.../selftests/bpf/benchs/bench_strncmp.c | 150 ++++++++++++++++++
.../selftests/bpf/benchs/run_bench_strncmp.sh | 12 ++
.../selftests/bpf/progs/strncmp_bench.c | 50 ++++++
5 files changed, 221 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/bpf/benchs/bench_strncmp.c
create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh
create mode 100644 tools/testing/selftests/bpf/progs/strncmp_bench.c
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 8ff7060fe754..7719924b01a3 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -531,6 +531,7 @@ $(OUTPUT)/bench_trigger.o: $(OUTPUT)/trigger_bench.skel.h
$(OUTPUT)/bench_ringbufs.o: $(OUTPUT)/ringbuf_bench.skel.h \
$(OUTPUT)/perfbuf_bench.skel.h
$(OUTPUT)/bench_bloom_filter_map.o: $(OUTPUT)/bloom_filter_bench.skel.h
+$(OUTPUT)/bench_strncmp.o: $(OUTPUT)/strncmp_bench.skel.h
$(OUTPUT)/bench.o: bench.h testing_helpers.h $(BPFOBJ)
$(OUTPUT)/bench: LDLIBS += -lm
$(OUTPUT)/bench: $(OUTPUT)/bench.o \
@@ -540,7 +541,8 @@ $(OUTPUT)/bench: $(OUTPUT)/bench.o \
$(OUTPUT)/bench_rename.o \
$(OUTPUT)/bench_trigger.o \
$(OUTPUT)/bench_ringbufs.o \
- $(OUTPUT)/bench_bloom_filter_map.o
+ $(OUTPUT)/bench_bloom_filter_map.o \
+ $(OUTPUT)/bench_strncmp.o
$(call msg,BINARY,,$@)
$(Q)$(CC) $(LDFLAGS) $(filter %.a %.o,$^) $(LDLIBS) -o $@
diff --git a/tools/testing/selftests/bpf/bench.c b/tools/testing/selftests/bpf/bench.c
index 681db8175fe1..8f1a4351fb18 100644
--- a/tools/testing/selftests/bpf/bench.c
+++ b/tools/testing/selftests/bpf/bench.c
@@ -184,10 +184,12 @@ static const struct argp_option opts[] = {
extern struct argp bench_ringbufs_argp;
extern struct argp bench_bloom_map_argp;
+extern struct argp strncmp_argp;
static const struct argp_child bench_parsers[] = {
{ &bench_ringbufs_argp, 0, "Ring buffers benchmark", 0 },
{ &bench_bloom_map_argp, 0, "Bloom filter map benchmark", 0 },
+ { &strncmp_argp, 0, "Strncmp benchmark", 0 },
{},
};
@@ -386,6 +388,8 @@ extern const struct bench bench_bloom_update;
extern const struct bench bench_bloom_false_positive;
extern const struct bench bench_hashmap_without_bloom;
extern const struct bench bench_hashmap_with_bloom;
+extern const struct bench bench_strncmp_no_helper;
+extern const struct bench bench_strncmp_helper;
static const struct bench *benchs[] = {
&bench_count_global,
@@ -417,6 +421,8 @@ static const struct bench *benchs[] = {
&bench_bloom_false_positive,
&bench_hashmap_without_bloom,
&bench_hashmap_with_bloom,
+ &bench_strncmp_no_helper,
+ &bench_strncmp_helper,
};
static void setup_benchmark()
diff --git a/tools/testing/selftests/bpf/benchs/bench_strncmp.c b/tools/testing/selftests/bpf/benchs/bench_strncmp.c
new file mode 100644
index 000000000000..57dea095e27a
--- /dev/null
+++ b/tools/testing/selftests/bpf/benchs/bench_strncmp.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <argp.h>
+#include "bench.h"
+#include "strncmp_bench.skel.h"
+
+struct strncmp_ctx {
+ struct strncmp_bench *skel;
+};
+
+struct strncmp_args {
+ u32 cmp_str_len;
+};
+
+static struct strncmp_args args = {
+ .cmp_str_len = 32,
+};
+
+static struct strncmp_ctx ctx;
+
+enum {
+ ARG_CMP_STR_LEN = 4000,
+};
+
+static const struct argp_option opts[] = {
+ { "cmp-str-len", ARG_CMP_STR_LEN, "CMP_STR_LEN", 0,
+ "Set the length of compared string" },
+ {},
+};
+
+static error_t strncmp_parse_arg(int key, char *arg, struct argp_state *state)
+{
+ switch (key) {
+ case ARG_CMP_STR_LEN:
+ args.cmp_str_len = strtoul(arg, NULL, 10);
+ if (!args.cmp_str_len ||
+ args.cmp_str_len >= sizeof(ctx.skel->bss->str)) {
+ fprintf(stderr, "Invalid cmp str len (limit %zu)\n",
+ sizeof(ctx.skel->bss->str));
+ argp_usage(state);
+ }
+ break;
+ default:
+ return ARGP_ERR_UNKNOWN;
+ }
+
+ return 0;
+}
+
+const struct argp strncmp_argp = {
+ .options = opts,
+ .parser = strncmp_parse_arg,
+};
+
+static void strncmp_validate(void)
+{
+ assert_single_consumer("strncmp");
+}
+
+static void strncmp_setup(void)
+{
+ int err;
+ char *target;
+ size_t i, sz;
+
+ sz = sizeof(ctx.skel->rodata->target);
+ if (!sz || sz < sizeof(ctx.skel->bss->str)) {
+ fprintf(stderr, "invalid string size (target %zu, src %zu)\n",
+ sz, sizeof(ctx.skel->bss->str));
+ exit(1);
+ }
+
+ setup_libbpf();
+
+ ctx.skel = strncmp_bench__open();
+ if (!ctx.skel) {
+ fprintf(stderr, "failed to open skeleton\n");
+ exit(1);
+ }
+
+ srandom(time(NULL));
+ target = ctx.skel->rodata->target;
+ for (i = 0; i < sz - 1; i++)
+ target[i] = '1' + random() % 9;
+ target[sz - 1] = '\0';
+
+ ctx.skel->rodata->cmp_str_len = args.cmp_str_len;
+
+ memcpy(ctx.skel->bss->str, target, args.cmp_str_len);
+ ctx.skel->bss->str[args.cmp_str_len] = '\0';
+ /* Make bss->str < rodata->target */
+ ctx.skel->bss->str[args.cmp_str_len - 1] -= 1;
+
+ err = strncmp_bench__load(ctx.skel);
+ if (err) {
+ fprintf(stderr, "failed to load skeleton\n");
+ strncmp_bench__destroy(ctx.skel);
+ exit(1);
+ }
+}
+
+static void strncmp_attach_prog(struct bpf_program *prog)
+{
+ struct bpf_link *link;
+
+ link = bpf_program__attach(prog);
+ if (!link) {
+ fprintf(stderr, "failed to attach program!\n");
+ exit(1);
+ }
+}
+
+static void strncmp_no_helper_setup(void)
+{
+ strncmp_setup();
+ strncmp_attach_prog(ctx.skel->progs.strncmp_no_helper);
+}
+
+static void strncmp_helper_setup(void)
+{
+ strncmp_setup();
+ strncmp_attach_prog(ctx.skel->progs.strncmp_helper);
+}
+
+static void strncmp_measure(struct bench_res *res)
+{
+ res->hits = atomic_swap(&ctx.skel->bss->hits, 0);
+}
+
+const struct bench bench_strncmp_no_helper = {
+ .name = "strncmp-no-helper",
+ .validate = strncmp_validate,
+ .setup = strncmp_no_helper_setup,
+ .producer_thread = getpgid_loop_producer,
+ .consumer_thread = noop_consumer,
+ .measure = strncmp_measure,
+ .report_progress = hits_drops_report_progress,
+ .report_final = hits_drops_report_final,
+};
+
+const struct bench bench_strncmp_helper = {
+ .name = "strncmp-helper",
+ .validate = strncmp_validate,
+ .setup = strncmp_helper_setup,
+ .producer_thread = getpgid_loop_producer,
+ .consumer_thread = noop_consumer,
+ .measure = strncmp_measure,
+ .report_progress = hits_drops_report_progress,
+ .report_final = hits_drops_report_final,
+};
diff --git a/tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh b/tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh
new file mode 100755
index 000000000000..142697284b45
--- /dev/null
+++ b/tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh
@@ -0,0 +1,12 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source ./benchs/run_common.sh
+
+set -eufo pipefail
+
+for s in 1 8 64 512 2048 4095; do
+ for b in no-helper helper; do
+ summarize ${b}-${s} "$($RUN_BENCH --cmp-str-len=$s strncmp-${b})"
+ done
+done
diff --git a/tools/testing/selftests/bpf/progs/strncmp_bench.c b/tools/testing/selftests/bpf/progs/strncmp_bench.c
new file mode 100644
index 000000000000..18373a7df76e
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/strncmp_bench.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2021. Huawei Technologies Co., Ltd */
+#include <linux/types.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+#define STRNCMP_STR_SZ 4096
+
+/* Will be updated by benchmark before program loading */
+const volatile unsigned int cmp_str_len = 1;
+const char target[STRNCMP_STR_SZ];
+
+long hits = 0;
+char str[STRNCMP_STR_SZ];
+
+char _license[] SEC("license") = "GPL";
+
+static __always_inline int local_strncmp(const char *s1, unsigned int sz,
+ const char *s2)
+{
+ int ret = 0;
+ unsigned int i;
+
+ for (i = 0; i < sz; i++) {
+ /* E.g. 0xff > 0x31 */
+ ret = (unsigned char)s1[i] - (unsigned char)s2[i];
+ if (ret || !s1[i])
+ break;
+ }
+
+ return ret;
+}
+
+SEC("tp/syscalls/sys_enter_getpgid")
+int strncmp_no_helper(void *ctx)
+{
+ if (local_strncmp(str, cmp_str_len + 1, target) < 0)
+ __sync_add_and_fetch(&hits, 1);
+ return 0;
+}
+
+SEC("tp/syscalls/sys_enter_getpgid")
+int strncmp_helper(void *ctx)
+{
+ if (bpf_strncmp(str, cmp_str_len + 1, target) < 0)
+ __sync_add_and_fetch(&hits, 1);
+ return 0;
+}
+
--
2.29.2
