[RFC bpf-next v2 1/4] selftests/bpf: Add benchmark for bpf memory allocator

[Hou Tao <houtao@huaweicloud.com>]

From: Hou Tao <houtao1@huawei.com>

The benchmark could be used to compare the performance of hash map
operations and the memory usage between different flavors of bpf memory
allocator (e.g., no bpf ma vs bpf ma vs reuse-after-gp bpf ma). It also
could be used to check the performance improvement or the memory saving
of bpf memory allocator optimization and check whether or not a specific
use case is suitable for bpf memory allocator.

The benchmark creates a non-preallocated hash map which uses bpf memory
allocator and shows the operation performance and the memory usage of
the hash map under different use cases:
(1) no_op
Only create the hash map and there is no operations on hash map. It is
used as the baseline. When each CPUs complete the iteartion of
nonoverlapping part of hash map, the loop count is increased.
(2) overwrite
Each CPU overwrites nonoverlapping part of hash map. When each CPU
completes one round of iteration, the loop count is increased.
(3) batch_add_batch_del
Each CPU adds then deletes nonoverlapping part of hash map in batch.
When each CPU completes one round of iteration, the loop count is
increased.
(4) add_del_on_diff_cpu
Each two CPUs add and delete nonoverlapping part of map concurrently.
When each CPU completes one round of iteration, the loop count is
increased.

The following benchmark results show that bpf memory allocator doesn't
handle add_del_on_diff_cpu scenario very well. Because map deletion
always happen on a different CPU than the map addition and the freed
memory can never be reused.

./bench htab-mem --use-case $name --max-entries 16384 \
	--full 50 -d 7 -w 3 --producers=8 --prod-affinity=0-7

| name                | loop (k/s) | average memory (MiB) | peak memory (MiB) |
| --                  | --         | --                   | --                |
| no_op               | 1129       | 1.15                 | 1.15              |
| overwrite           | 24.37      | 2.07                 | 2.97              |
| batch_add_batch_del | 10.58      | 2.91                 | 3.36              |
| add_del_on_diff_cpu | 13.14      | 380.66               | 633.99            |

./bench htab-mem --preallocated --use-case $name --max-entries 16384 \
	--full 50 -d 7 -w 3 --producers=8 --prod-affinity=0-7

| name                | loop (k/s) | average memory (MiB) | peak memory (MiB) |
| --                  | --         | --                   | --                |
| no_op               | 1195       | 2.11                 | 2.16              |
| overwrite           | 34.02      | 1.96                 | 2.00              |
| batch_add_batch_del | 19.25      | 1.96                 | 2.00              |
| add_del_on_diff_cpu | 8.70       | 1.96                 | 2.00              |

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
 tools/testing/selftests/bpf/Makefile          |   3 +
 tools/testing/selftests/bpf/bench.c           |   4 +
 .../selftests/bpf/benchs/bench_htab_mem.c     | 273 ++++++++++++++++++
 .../selftests/bpf/progs/htab_mem_bench.c      | 145 ++++++++++
 4 files changed, 425 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/benchs/bench_htab_mem.c
 create mode 100644 tools/testing/selftests/bpf/progs/htab_mem_bench.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index c02184eaae69..74a45c790d4a 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -647,11 +647,13 @@ $(OUTPUT)/bench_local_storage.o: $(OUTPUT)/local_storage_bench.skel.h
 $(OUTPUT)/bench_local_storage_rcu_tasks_trace.o: $(OUTPUT)/local_storage_rcu_tasks_trace_bench.skel.h
 $(OUTPUT)/bench_local_storage_create.o: $(OUTPUT)/bench_local_storage_create.skel.h
 $(OUTPUT)/bench_bpf_hashmap_lookup.o: $(OUTPUT)/bpf_hashmap_lookup.skel.h
+$(OUTPUT)/bench_htab_mem.o: $(OUTPUT)/htab_mem_bench.skel.h
 $(OUTPUT)/bench.o: bench.h testing_helpers.h $(BPFOBJ)
 $(OUTPUT)/bench: LDLIBS += -lm
 $(OUTPUT)/bench: $(OUTPUT)/bench.o \
 		 $(TESTING_HELPERS) \
 		 $(TRACE_HELPERS) \
+		 $(CGROUP_HELPERS) \
 		 $(OUTPUT)/bench_count.o \
 		 $(OUTPUT)/bench_rename.o \
 		 $(OUTPUT)/bench_trigger.o \
@@ -664,6 +666,7 @@ $(OUTPUT)/bench: $(OUTPUT)/bench.o \
 		 $(OUTPUT)/bench_local_storage_rcu_tasks_trace.o \
 		 $(OUTPUT)/bench_bpf_hashmap_lookup.o \
 		 $(OUTPUT)/bench_local_storage_create.o \
+		 $(OUTPUT)/bench_htab_mem.o \
 		 #
 	$(call msg,BINARY,,$@)
 	$(Q)$(CC) $(CFLAGS) $(LDFLAGS) $(filter %.a %.o,$^) $(LDLIBS) -o $@
diff --git a/tools/testing/selftests/bpf/bench.c b/tools/testing/selftests/bpf/bench.c
index d9c080ac1796..d3d9ae321b74 100644
--- a/tools/testing/selftests/bpf/bench.c
+++ b/tools/testing/selftests/bpf/bench.c
@@ -279,6 +279,7 @@ extern struct argp bench_local_storage_rcu_tasks_trace_argp;
 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;
 
 static const struct argp_child bench_parsers[] = {
 	{ &bench_ringbufs_argp, 0, "Ring buffers benchmark", 0 },
@@ -290,6 +291,7 @@ static const struct argp_child bench_parsers[] = {
 		"local_storage RCU Tasks Trace slowdown benchmark", 0 },
 	{ &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 },
 	{},
 };
 
@@ -518,6 +520,7 @@ extern const struct bench bench_local_storage_cache_hashmap_control;
 extern const struct bench bench_local_storage_tasks_trace;
 extern const struct bench bench_bpf_hashmap_lookup;
 extern const struct bench bench_local_storage_create;
+extern const struct bench bench_htab_mem;
 
 static const struct bench *benchs[] = {
 	&bench_count_global,
@@ -559,6 +562,7 @@ static const struct bench *benchs[] = {
 	&bench_local_storage_tasks_trace,
 	&bench_bpf_hashmap_lookup,
 	&bench_local_storage_create,
+	&bench_htab_mem,
 };
 
 static void find_benchmark(void)
diff --git a/tools/testing/selftests/bpf/benchs/bench_htab_mem.c b/tools/testing/selftests/bpf/benchs/bench_htab_mem.c
new file mode 100644
index 000000000000..116821a2a7dd
--- /dev/null
+++ b/tools/testing/selftests/bpf/benchs/bench_htab_mem.c
@@ -0,0 +1,273 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
+#include <argp.h>
+#include <stdbool.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "bench.h"
+#include "cgroup_helpers.h"
+#include "htab_mem_bench.skel.h"
+
+static struct htab_mem_ctx {
+	struct htab_mem_bench *skel;
+	int fd;
+} ctx;
+
+static struct htab_mem_args {
+	u32 max_entries;
+	u32 value_size;
+	u32 full;
+	const char *use_case;
+	bool preallocated;
+} args = {
+	.max_entries = 16384,
+	.full = 50,
+	.value_size = 8,
+	.use_case = "overwrite",
+	.preallocated = false,
+};
+
+enum {
+	ARG_MAX_ENTRIES = 10000,
+	ARG_FULL_PERCENT = 10001,
+	ARG_VALUE_SIZE = 10002,
+	ARG_USE_CASE = 10003,
+	ARG_PREALLOCATED = 10004,
+};
+
+static const struct argp_option opts[] = {
+	{ "max-entries", ARG_MAX_ENTRIES, "MAX_ENTRIES", 0,
+	  "Set the max entries of hash map (default 16384)" },
+	{ "full", ARG_FULL_PERCENT, "FULL", 0,
+	  "Set the full percent of hash map (default 50)" },
+	{ "value-size", ARG_VALUE_SIZE, "VALUE_SIZE", 0,
+	  "Set the value size of hash map (default 8)" },
+	{ "use-case", ARG_USE_CASE, "USE_CASE", 0,
+	  "Set the use case of hash map: no_op|overwrite|batch_add_batch_del|add_del_on_diff_cpu" },
+	{ "preallocated", ARG_PREALLOCATED, NULL, 0, "use preallocated hash map" },
+	{},
+};
+
+static error_t htab_mem_parse_arg(int key, char *arg, struct argp_state *state)
+{
+	switch (key) {
+	case ARG_MAX_ENTRIES:
+		args.max_entries = strtoul(arg, NULL, 10);
+		break;
+	case ARG_FULL_PERCENT:
+		args.full = strtoul(arg, NULL, 10);
+		if (!args.full || args.full > 100) {
+			fprintf(stderr, "invalid full percent %u\n", args.full);
+			argp_usage(state);
+		}
+		break;
+	case ARG_VALUE_SIZE:
+		args.value_size = strtoul(arg, NULL, 10);
+		break;
+	case ARG_USE_CASE:
+		args.use_case = strdup(arg);
+		break;
+	case ARG_PREALLOCATED:
+		args.preallocated = true;
+		break;
+	default:
+		return ARGP_ERR_UNKNOWN;
+	}
+
+	return 0;
+}
+
+const struct argp bench_htab_mem_argp = {
+	.options = opts,
+	.parser = htab_mem_parse_arg,
+};
+
+static void htab_mem_validate(void)
+{
+	if (env.consumer_cnt != 1) {
+		fprintf(stderr, "htab mem benchmark doesn't support multi-consumer!\n");
+		exit(1);
+	}
+}
+
+static int setup_and_join_cgroup(const char *path)
+{
+	int err, fd;
+
+	err = setup_cgroup_environment();
+	if (err) {
+		fprintf(stderr, "setup cgroup env failed\n");
+		return -1;
+	}
+
+	err = create_and_get_cgroup(path);
+	if (err < 0) {
+		fprintf(stderr, "create cgroup %s failed\n", path);
+		goto out;
+	}
+	fd = err;
+
+	err = join_cgroup(path);
+	if (err) {
+		fprintf(stderr, "join cgroup %s failed\n", path);
+		close(fd);
+		goto out;
+	}
+
+	return fd;
+out:
+	cleanup_cgroup_environment();
+	return -1;
+}
+
+static void htab_mem_setup(void)
+{
+	struct bpf_program *prog;
+	struct bpf_map *map;
+	int err;
+
+	setup_libbpf();
+
+	err = setup_and_join_cgroup("/htab_mem");
+	if (err < 0)
+		exit(1);
+	ctx.fd = err;
+
+	ctx.skel = htab_mem_bench__open();
+	if (!ctx.skel) {
+		fprintf(stderr, "failed to open skeleton\n");
+		goto cleanup;
+	}
+
+	map = ctx.skel->maps.htab;
+	bpf_map__set_max_entries(map, args.max_entries);
+	bpf_map__set_value_size(map, args.value_size);
+	if (args.preallocated)
+		bpf_map__set_map_flags(map, bpf_map__map_flags(map) & ~BPF_F_NO_PREALLOC);
+
+	map = ctx.skel->maps.array;
+	bpf_map__set_max_entries(map, args.max_entries);
+	bpf_map__set_value_size(map, args.value_size);
+
+	prog = bpf_object__find_program_by_name(ctx.skel->obj, args.use_case);
+	if (!prog) {
+		fprintf(stderr, "no such use-case: %s\n", args.use_case);
+		fprintf(stderr, "available use case:");
+		bpf_object__for_each_program(prog, ctx.skel->obj)
+			fprintf(stderr, " %s", bpf_program__name(prog));
+		fprintf(stderr, "\n");
+		goto cleanup;
+	}
+	bpf_program__set_autoload(prog, true);
+
+	ctx.skel->bss->nr_thread = env.producer_cnt;
+	ctx.skel->bss->nr_entries = (uint64_t)args.max_entries * args.full / 100;
+
+	err = htab_mem_bench__load(ctx.skel);
+	if (err) {
+		fprintf(stderr, "failed to load skeleton\n");
+		goto cleanup;
+	}
+	err = htab_mem_bench__attach(ctx.skel);
+	if (err) {
+		fprintf(stderr, "failed to attach skeleton\n");
+		goto cleanup;
+	}
+	return;
+cleanup:
+	close(ctx.fd);
+	cleanup_cgroup_environment();
+	htab_mem_bench__destroy(ctx.skel);
+	exit(1);
+}
+
+static void *htab_mem_producer(void *ctx)
+{
+	while (true)
+		(void)syscall(__NR_getpgid);
+	return NULL;
+}
+
+static void *htab_mem_consumer(void *ctx)
+{
+	return NULL;
+}
+
+static void htab_mem_read_mem_cgrp_file(const char *name, unsigned long *value)
+{
+	char buf[32];
+	int fd;
+
+	fd = openat(ctx.fd, name, O_RDONLY);
+	if (fd < 0) {
+		fprintf(stderr, "no %s\n", name);
+		*value = 0;
+		return;
+	}
+
+	buf[sizeof(buf) - 1] = 0;
+	read(fd, buf, sizeof(buf) - 1);
+	*value = strtoull(buf, NULL, 0);
+
+	close(fd);
+}
+
+static void htab_mem_measure(struct bench_res *res)
+{
+	res->hits = atomic_swap(&ctx.skel->bss->loop_cnt, 0);
+	htab_mem_read_mem_cgrp_file("memory.current", &res->gp_ct);
+}
+
+static void htab_mem_report_progress(int iter, struct bench_res *res, long delta_ns)
+{
+	double loop, mem;
+
+	loop = res->hits / 1000.0 / (delta_ns / 1000000000.0);
+	mem = res->gp_ct / 1048576.0;
+	printf("Iter %3d (%7.3lfus): ", iter, (delta_ns - 1000000000) / 1000.0);
+	printf("loop %7.2lfk/s, memory usage %7.2lfMiB\n", loop, mem);
+}
+
+static void htab_mem_report_final(struct bench_res res[], int res_cnt)
+{
+	double mem_mean = 0.0, mem_stddev = 0.0;
+	double loop_mean = 0.0, loop_stddev = 0.0;
+	unsigned long peak_mem;
+	int i;
+
+	for (i = 0; i < res_cnt; i++) {
+		loop_mean += res[i].hits / 1000.0 / (0.0 + res_cnt);
+		mem_mean += res[i].gp_ct / 1048576.0 / (0.0 + res_cnt);
+	}
+	if (res_cnt > 1)  {
+		for (i = 0; i < res_cnt; i++) {
+			loop_stddev += (loop_mean - res[i].hits / 1000.0) *
+				       (loop_mean - res[i].hits / 1000.0) /
+				       (res_cnt - 1.0);
+			mem_stddev += (mem_mean - res[i].gp_ct / 1048576.0) *
+				      (mem_mean - res[i].gp_ct / 1048576.0) /
+				      (res_cnt - 1.0);
+		}
+		loop_stddev = sqrt(loop_stddev);
+		mem_stddev = sqrt(mem_stddev);
+	}
+
+	htab_mem_read_mem_cgrp_file("memory.peak", &peak_mem);
+	printf("Summary: loop %7.2lf \u00B1 %7.2lfk/s, memory usage %7.2lf \u00B1 %7.2lfMiB, "
+	       "peak memory usage %7.2lfMiB\n",
+	       loop_mean, loop_stddev, mem_mean, mem_stddev, peak_mem / 1048576.0);
+}
+
+const struct bench bench_htab_mem = {
+	.name = "htab-mem",
+	.argp = &bench_htab_mem_argp,
+	.validate = htab_mem_validate,
+	.setup = htab_mem_setup,
+	.producer_thread = htab_mem_producer,
+	.consumer_thread = htab_mem_consumer,
+	.measure = htab_mem_measure,
+	.report_progress = htab_mem_report_progress,
+	.report_final = htab_mem_report_final,
+};
diff --git a/tools/testing/selftests/bpf/progs/htab_mem_bench.c b/tools/testing/selftests/bpf/progs/htab_mem_bench.c
new file mode 100644
index 000000000000..f320cb3a11e8
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/htab_mem_bench.c
@@ -0,0 +1,145 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
+#include <stdbool.h>
+#include <errno.h>
+#include <linux/types.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+struct update_ctx {
+	unsigned int from;
+	unsigned int step;
+	unsigned int max;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, 4);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+} htab SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(key_size, 4);
+} array SEC(".maps");
+
+char _license[] SEC("license") = "GPL";
+
+unsigned int nr_entries = 0;
+unsigned int nr_thread = 0;
+long loop_cnt = 0;
+
+static int noop_htab(unsigned int i, struct update_ctx *ctx)
+{
+	if (ctx->from >= ctx->max)
+		return 1;
+
+	ctx->from += ctx->step;
+	return 0;
+}
+
+static int write_htab(unsigned int i, struct update_ctx *ctx, unsigned int flags)
+{
+	__u64 *value;
+
+	if (ctx->from >= ctx->max)
+		return 1;
+
+	value = bpf_map_lookup_elem(&array, &ctx->from);
+	if (value)
+		bpf_map_update_elem(&htab, &ctx->from, value, flags);
+	ctx->from += ctx->step;
+
+	return 0;
+}
+
+static int overwrite_htab(unsigned int i, struct update_ctx *ctx)
+{
+	return write_htab(i, ctx, 0);
+}
+
+static int newwrite_htab(unsigned int i, struct update_ctx *ctx)
+{
+	return write_htab(i, ctx, BPF_NOEXIST);
+}
+
+static int del_htab(unsigned int i, struct update_ctx *ctx)
+{
+	__u64 *value;
+
+	if (ctx->from >= ctx->max)
+		return 1;
+
+	value = bpf_map_lookup_elem(&array, &ctx->from);
+	if (value)
+		bpf_map_delete_elem(&htab, &ctx->from);
+	ctx->from += ctx->step;
+
+	return 0;
+}
+
+SEC("?tp/syscalls/sys_enter_getpgid")
+int no_op(void *ctx)
+{
+	struct update_ctx update;
+
+	update.from = bpf_get_smp_processor_id();
+	update.step = nr_thread;
+	update.max = nr_entries;
+	bpf_loop(update.max, noop_htab, &update, 0);
+	__sync_fetch_and_add(&loop_cnt, 1);
+
+	return 0;
+}
+
+SEC("?tp/syscalls/sys_enter_getpgid")
+int overwrite(void *ctx)
+{
+	struct update_ctx update;
+
+	update.from = bpf_get_smp_processor_id();
+	update.step = nr_thread;
+	update.max = nr_entries;
+	bpf_loop(update.max, overwrite_htab, &update, 0);
+
+	__sync_fetch_and_add(&loop_cnt, 1);
+	return 0;
+}
+
+SEC("?tp/syscalls/sys_enter_getpgid")
+int batch_add_batch_del(void *ctx)
+{
+	struct update_ctx update;
+
+	update.from = bpf_get_smp_processor_id();
+	update.step = nr_thread;
+	update.max = nr_entries;
+	bpf_loop(update.max, overwrite_htab, &update, 0);
+
+	update.from = bpf_get_smp_processor_id();
+	bpf_loop(update.max, del_htab, &update, 0);
+
+	__sync_fetch_and_add(&loop_cnt, 1);
+	return 0;
+}
+
+SEC("?tp/syscalls/sys_enter_getpgid")
+int add_del_on_diff_cpu(void *ctx)
+{
+	struct update_ctx update;
+	unsigned int from;
+
+	from = bpf_get_smp_processor_id();
+	update.from = from / 2;
+	update.step = nr_thread / 2;
+	update.max = nr_entries;
+
+	if (from & 1)
+		bpf_loop(update.max, newwrite_htab, &update, 0);
+	else
+		bpf_loop(update.max, del_htab, &update, 0);
+
+	__sync_fetch_and_add(&loop_cnt, 1);
+	return 0;
+}
-- 
2.29.2