[PATCH bpf-next v5] 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
provided by optimization.

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 CPU completes the iteration of 64
elements in hash map, it increases the loop count.
(2) overwrite
Each CPU overwrites nonoverlapping part of hash map. When each CPU
completes overwriting of 64 elements in hash map, it increases the loop
count.
(3) batch_add_batch_del
Each CPU adds then deletes nonoverlapping part of hash map in batch.
When each CPU adds and deletes 64 elements in hash map, it increases the
loop count.
(4) add_del_on_diff_cpu
Each two-CPUs pair adds and deletes nonoverlapping part of map
cooperatively. When each pair adds and deletes 64 elements in hash map,
the two-CPUs pair will increase the loop count.

The following is the benchmark results when comparing between different
flavors of bpf memory allocator. These tests are conducted on a KVM guest
with 8 CPUs and 16 GB memory. The command line below is used to do all
the following benchmarks:

  ./bench htab-mem --use-case $name --max-entries 16384 ${OPTS} \
          --full 50 -d 10 --producers=8 --prod-affinity=0-7

These results show:
* preallocated case has both better performance and better memory
  efficiency.
* normal bpf memory doesn't handle add_del_on_diff_cpu very well. The
  large memory usage is due to the slow tasks trace RCU grace period.

(1) non-preallocated + no bpf memory allocator (v6.0.19)
use kmalloc() + call_rcu

| name               | loop (k/s)| average memory (MiB)| peak memory (MiB)|
| --                 | --        | --                  | --               |
| no_op              | 681.40    | 0.87                | 1.00             |
| overwrite          | 8.56      | 38.86               | 88.42            |
| batch_add_batch_del| 6.74      | 41.28               | 69.70            |
| add_del_on_diff_cpu| 4.68      | 3.43                | 5.70             |

(2) preallocated
OPTS=--preallocated

| name               | loop (k/s)| average memory (MiB)| peak memory (MiB)|
| --                 | --        | --                  | --               |
| no_op              | 673.95    | 1.98                | 1.98             |
| overwrite          | 114.63    | 1.99                | 1.99             |
| batch_add_batch_del| 78.34     | 2.04                | 2.06             |
| add_del_on_diff_cpu| 6.41      | 2.23                | 2.54             |

(3) normal bpf memory allocator

| name               | loop (k/s)| average memory (MiB)| peak memory (MiB)|
| --                 | --        | --                  | --               |
| no_op              | 656.20    | 0.99                | 0.99             |
| overwrite          | 81.21     | 1.10                | 2.49             |
| batch_add_batch_del| 18.40     | 2.13                | 2.62             |
| add_del_on_diff_cpu| 5.38      | 10.40               | 18.05            |

Signed-off-by: Hou Tao <houtao1@huawei.com>
---
v5:
 * send the benchmark patch alone (suggested by Alexei)
 * limit the max number of touched elements per-bpf-program call to 64 (from Alexei)
 * show per-producer performance (from Alexei)
 * handle the return value of read() (from BPF CI)
 * do cleanup_cgroup_environment() in htab_mem_report_final()

v4: https://lore.kernel.org/bpf/20230606035310.4026145-1-houtao@huaweicloud.com/

 tools/testing/selftests/bpf/Makefile          |   3 +
 tools/testing/selftests/bpf/bench.c           |   4 +
 .../selftests/bpf/benchs/bench_htab_mem.c     | 367 ++++++++++++++++++
 .../bpf/benchs/run_bench_htab_mem.sh          |  42 ++
 .../selftests/bpf/progs/htab_mem_bench.c      | 132 +++++++
 5 files changed, 548 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/benchs/bench_htab_mem.c
 create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_htab_mem.sh
 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 538df8fb8c42..add018823ebd 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -644,11 +644,13 @@ $(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 \
@@ -661,6 +663,7 @@ $(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..e658a9f1ce3c
--- /dev/null
+++ b/tools/testing/selftests/bpf/benchs/bench_htab_mem.c
@@ -0,0 +1,367 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
+#include <argp.h>
+#include <stdbool.h>
+#include <pthread.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;
+	pthread_barrier_t *notify;
+	int fd;
+	int op_factor;
+	bool do_notify_wait;
+} 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);
+		if (args.value_size > 4096) {
+			fprintf(stderr, "too big value size %u\n", args.value_size);
+			argp_usage(state);
+		}
+		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 int htab_mem_bench_init_barriers(void)
+{
+	unsigned int i, nr = (env.producer_cnt + 1) / 2;
+	pthread_barrier_t *barriers;
+
+	barriers = calloc(nr, sizeof(*barriers));
+	if (!barriers)
+		return -1;
+
+	/* Used for synchronization between two threads */
+	for (i = 0; i < nr; i++)
+		pthread_barrier_init(&barriers[i], NULL, 2);
+
+	ctx.notify = barriers;
+	return 0;
+}
+
+static void htab_mem_bench_exit_barriers(void)
+{
+	unsigned int i, nr;
+
+	if (!ctx.notify)
+		return;
+
+	nr = (env.producer_cnt + 1) / 2;
+	for (i = 0; i < nr; i++)
+		pthread_barrier_destroy(&ctx.notify[i]);
+	free(ctx.notify);
+}
+
+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;
+	}
+
+	err = htab_mem_bench_init_barriers();
+	if (err) {
+		fprintf(stderr, "failed to init barrier\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);
+
+	if (!strcmp("add_del_on_diff_cpu", args.use_case)) {
+		/* Do synchronization between addition thread and deletion thread */
+		ctx.do_notify_wait = true;
+		/* Use two CPUs to do addition and deletion cooperatively */
+		ctx.op_factor = 2;
+	} else {
+		ctx.op_factor = 1;
+	}
+
+	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_exit_barriers();
+	htab_mem_bench__destroy(ctx.skel);
+	exit(1);
+}
+
+static void htab_mem_notify_wait_producer(pthread_barrier_t *notify)
+{
+	while (true) {
+		(void)syscall(__NR_getpgid);
+		/* Notify for start */
+		pthread_barrier_wait(notify);
+		/* Wait for completion */
+		pthread_barrier_wait(notify);
+	}
+}
+
+static void htab_mem_wait_notify_producer(pthread_barrier_t *notify)
+{
+	while (true) {
+		/* Wait for start */
+		pthread_barrier_wait(notify);
+		(void)syscall(__NR_getpgid);
+		/* Notify for completion */
+		pthread_barrier_wait(notify);
+	}
+}
+
+static void *htab_mem_producer(void *arg)
+{
+	pthread_barrier_t *notify;
+	int seq;
+
+	if (!ctx.do_notify_wait) {
+		while (true)
+			(void)syscall(__NR_getpgid);
+		return NULL;
+	}
+
+	seq = (long)arg;
+	notify = &ctx.notify[seq / 2];
+	if (seq & 1)
+		htab_mem_notify_wait_producer(notify);
+	else
+		htab_mem_wait_notify_producer(notify);
+	return NULL;
+}
+
+static void *htab_mem_consumer(void *arg)
+{
+	return NULL;
+}
+
+static void htab_mem_read_mem_cgrp_file(const char *name, unsigned long *value)
+{
+	char buf[32];
+	ssize_t got;
+	int fd;
+
+	fd = openat(ctx.fd, name, O_RDONLY);
+	if (fd < 0) {
+		/* cgroup v1 ? */
+		fprintf(stderr, "no %s\n", name);
+		*value = 0;
+		return;
+	}
+
+	got = read(fd, buf, sizeof(buf) - 1);
+	if (got <= 0) {
+		*value = 0;
+		return;
+	}
+	buf[got] = 0;
+
+	*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) / env.producer_cnt / ctx.op_factor;
+	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("per-prod-op %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;
+
+	cleanup_cgroup_environment();
+
+	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: per-prod-op %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/benchs/run_bench_htab_mem.sh b/tools/testing/selftests/bpf/benchs/run_bench_htab_mem.sh
new file mode 100755
index 000000000000..630c02f859cf
--- /dev/null
+++ b/tools/testing/selftests/bpf/benchs/run_bench_htab_mem.sh
@@ -0,0 +1,42 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source ./benchs/run_common.sh
+
+set -eufo pipefail
+
+htab_mem()
+{
+	echo -n "per-prod-op : "
+	echo -n "$*" | sed -E "s/.* per-prod-op\s+([0-9]+\.[0-9]+ ± [0-9]+\.[0-9]+k\/s).*/\1/"
+	echo -n -e ", avg mem: "
+	echo -n "$*" | sed -E "s/.* memory usage\s+([0-9]+\.[0-9]+ ± [0-9]+\.[0-9]+MiB).*/\1/"
+	echo -n ", peak mem: "
+	echo "$*" | sed -E "s/.* peak memory usage\s+([0-9]+\.[0-9]+MiB).*/\1/"
+}
+
+summarize_htab_mem()
+{
+	local bench="$1"
+	local summary=$(echo $2 | tail -n1)
+
+	printf "%-20s %s\n" "$bench" "$(htab_mem $summary)"
+}
+
+htab_mem_bench()
+{
+	local name
+
+	for name in no_op overwrite batch_add_batch_del add_del_on_diff_cpu
+	do
+		summarize_htab_mem "$name" "$(sudo ./bench htab-mem --use-case $name \
+			--max-entries 16384 --full 50 -d 10 \
+			--producers=8 --prod-affinity=0-7 "$@")"
+	done
+}
+
+header "preallocated"
+htab_mem_bench "--preallocated"
+
+header "normal bpf ma"
+htab_mem_bench
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..a1a5981df865
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/htab_mem_bench.c
@@ -0,0 +1,132 @@
+// 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");
+
+char _license[] SEC("license") = "GPL";
+
+unsigned char zeroed_value[4096];
+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)
+{
+	if (ctx->from >= ctx->max)
+		return 1;
+
+	bpf_map_update_elem(&htab, &ctx->from, zeroed_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)
+{
+	if (ctx->from >= ctx->max)
+		return 1;
+
+	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(64, 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(64, 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(64, overwrite_htab, &update, 0);
+
+	update.from = bpf_get_smp_processor_id();
+	bpf_loop(64, 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(64, newwrite_htab, &update, 0);
+	else
+		bpf_loop(64, del_htab, &update, 0);
+
+	__sync_fetch_and_add(&loop_cnt, 1);
+	return 0;
+}
-- 
2.29.2