Hi,
On 6/9/2023 11:19 AM, Alexei Starovoitov wrote:
> On Fri, Jun 09, 2023 at 10:40:30AM +0800, Hou Tao wrote:
>> From: Hou Tao <houtao1@xxxxxxxxxx>
>>
>> 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.
> I think this no_op is pointless. It cannot be compared to anything.
> Please remove.
Will do.
>
>> (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.
> ...
>> | add_del_on_diff_cpu| 5.38 | 10.40 | 18.05 |
> Doesn't handle well with 18Mbyte peak memory ?
> I think it's the opposite.
> rcu task trace and slab are handling it very well.
>
>> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
>> ---
>> 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@xxxxxxxxxxxxxxx/
>>
>> 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;
>> + }
> Please remove op_factor and just do loop += 2 where necessary.
OK. Will fix.
>
>> +
>> + 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 $name \
>> + --max-entries 16384 --full 50 -d 10 \
> -d 10 is a default. why specify it?
Er, the default duration is 5 seconds. But I think it is OK to remove it.
>
>> + --producers=8 --prod-affinity=0-7 "$@")"
> -a -p 8 should just work.
> No need to pick specific cpus.
No. For VM with only 8 CPUs, the affinity of the first producer will be
CPU 1 and the affinity of the last producer will be CPU 8, so the
benchmark will fail to run. But I think I can fix it, so the affinity of
the last producer will be 0 instead.
>
>> + 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);
> This is sloppy, since it makes --max_entries and --full arguments useless.
> Either make them meaningful or hard code size of htab and remove these args.
OK. Will check how to do that. Hard code the size of htab is indeed much
simpler.
>
>> + __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);
> It probably should be loop_cnt += 2
> because two map operations of 64 each are performed comparing to single
> op of 64 in "overwrite".
Will fix.
>
>> + 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);
> op_factor=2 doesn't make sense here.
> One cpu is doing map_update while another cpu is doing map_delete.
> Both cpus are doing loop_cnt+=1.
> It's fine to keep loop_cnt+=1 here and remove op_factor.
>
> Also what happens if number of producers is odd?
For the producer without cooperator, it will hang for the wake-up and
getpgid() will never be called. The add_del_on_diff_cpu test needs
even-numbered producer. Will enforce that during validation.
>
> The summary of all comments is please design this bench that it's:
> 1. realistic and tests something that can happen with real progs
> 2. combination of all knobs and flags is meaningful.
Thanks for these suggestions.
> .
