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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-08-09 06:14:34 +02:00
Support resizable hashmap in BPF map benchmarks.
1. LOOKUP (single producer, M events/sec)
key | max | nr | htab | rhtab | ratio | delta
----+-----+-------+---------+---------+-------+-------
8 | 1K | 750 | 99.85 | 81.92 | 0.82x | -18 %
8 | 1K | 1K | 100.71 | 80.19 | 0.80x | -20 %
8 | 1M | 750K | 23.37 | 72.09 | 3.08x | +208 %
8 | 1M | 1M | 13.39 | 53.72 | 4.01x | +301 %
32 | 1K | 750 | 51.57 | 42.78 | 0.83x | -17 %
32 | 1K | 1K | 50.81 | 45.83 | 0.90x | -10 %
32 | 1M | 750K | 11.27 | 15.29 | 1.36x | +36 %
32 | 1M | 1M | 7.32 | 8.75 | 1.19x | +19 %
256 | 1K | 750 | 7.58 | 7.88 | 1.04x | +4 %
256 | 1K | 1K | 7.43 | 7.81 | 1.05x | +5 %
256 | 1M | 750K | 3.69 | 4.27 | 1.16x | +16 %
256 | 1M | 1M | 2.60 | 3.12 | 1.20x | +20 %
Pattern:
* Small map (1K): htab wins for 8 / 32 byte keys by 10-20%
* Large map (1M): rhtab wins everywhere, up to 4x at high load
factor with 8 byte keys.
* Higher load factor amplifies rhtab's lead: rhtab grows the
bucket array; htab stays at user-declared max.
2. FULL UPDATE (M events/sec per producer)
htab per-producer:
20.33 22.02 19.27 23.61 24.18 23.17 21.07
mean 21.94 range 19.27 - 24.18
rhtab per-producer:
133.51 129.47 74.52 129.29 102.26 129.98 107.64
mean 115.24 range 74.52 - 133.51
speedup (mean): 5.25x (+425 %)
In-place memcpy avoids the per-update alloc + RCU pointer swap
that htab pays.
3. MEMORY
value_size | htab ops/s | rhtab ops/s | htab mem | rhtab mem
-----------+-------------+-------------+----------+----------
32 B | 122.87 k/s | 133.04 k/s | 2.47 MiB | 2.49 MiB
4096 B | 64.43 k/s | 65.38 k/s | 6.74 MiB | 6.44 MiB
rhtab/htab : +8 % ops, +0.8 % mem (32 B)
+1 % ops, -4 % mem (4096 B)
Throughput effectively tied
SUMMARY
* Small / well-fitting map: htab is faster (cache-friendly
fixed bucket array), but only by ~10-20 %.
* Large / high-load-factor map: rhtab is dramatically faster
(1.2x to 4x) because rhashtable resizes to keep the load
factor sane while htab stays stuck at user-declared max.
* Update-heavy workloads: rhtab is ~5x faster per producer
via in-place memcpy.
* Memory benchmark: effectively on par.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260605-rhash-v7-12-5b8e05f8630d@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
382 lines
8.8 KiB
C
382 lines
8.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (C) 2023. Huawei Technologies Co., Ltd */
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#include <argp.h>
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#include <stdbool.h>
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#include <pthread.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/param.h>
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#include <fcntl.h>
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#include "bench.h"
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#include "bpf_util.h"
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#include "cgroup_helpers.h"
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#include "htab_mem_bench.skel.h"
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struct htab_mem_use_case {
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const char *name;
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const char **progs;
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/* Do synchronization between addition thread and deletion thread */
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bool need_sync;
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};
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static struct htab_mem_ctx {
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const struct htab_mem_use_case *uc;
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struct htab_mem_bench *skel;
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pthread_barrier_t *notify;
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int fd;
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} ctx;
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const char *ow_progs[] = {"overwrite", NULL};
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const char *batch_progs[] = {"batch_add_batch_del", NULL};
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const char *add_del_progs[] = {"add_only", "del_only", NULL};
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const static struct htab_mem_use_case use_cases[] = {
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{ .name = "overwrite", .progs = ow_progs },
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{ .name = "batch_add_batch_del", .progs = batch_progs },
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{ .name = "add_del_on_diff_cpu", .progs = add_del_progs, .need_sync = true },
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};
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static struct htab_mem_args {
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u32 value_size;
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const char *use_case;
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bool preallocated;
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} args = {
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.value_size = 8,
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.use_case = "overwrite",
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.preallocated = false,
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};
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enum {
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ARG_VALUE_SIZE = 10000,
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ARG_USE_CASE = 10001,
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ARG_PREALLOCATED = 10002,
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};
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static const struct argp_option opts[] = {
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{ "value-size", ARG_VALUE_SIZE, "VALUE_SIZE", 0,
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"Set the value size of hash map (default 8)" },
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{ "use-case", ARG_USE_CASE, "USE_CASE", 0,
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"Set the use case of hash map: overwrite|batch_add_batch_del|add_del_on_diff_cpu" },
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{ "preallocated", ARG_PREALLOCATED, NULL, 0, "use preallocated hash map" },
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{},
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};
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static error_t htab_mem_parse_arg(int key, char *arg, struct argp_state *state)
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{
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switch (key) {
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case ARG_VALUE_SIZE:
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args.value_size = strtoul(arg, NULL, 10);
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if (args.value_size > 4096) {
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fprintf(stderr, "too big value size %u\n", args.value_size);
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argp_usage(state);
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}
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break;
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case ARG_USE_CASE:
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args.use_case = strdup(arg);
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if (!args.use_case) {
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fprintf(stderr, "no mem for use-case\n");
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argp_usage(state);
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}
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break;
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case ARG_PREALLOCATED:
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args.preallocated = true;
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break;
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default:
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return ARGP_ERR_UNKNOWN;
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}
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return 0;
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}
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const struct argp bench_htab_mem_argp = {
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.options = opts,
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.parser = htab_mem_parse_arg,
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};
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static void htab_mem_validate(void)
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{
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if (!strcmp(use_cases[2].name, args.use_case) && env.producer_cnt % 2) {
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fprintf(stderr, "%s needs an even number of producers\n", args.use_case);
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exit(1);
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}
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}
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static int htab_mem_bench_init_barriers(void)
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{
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pthread_barrier_t *barriers;
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unsigned int i, nr;
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if (!ctx.uc->need_sync)
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return 0;
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nr = (env.producer_cnt + 1) / 2;
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barriers = calloc(nr, sizeof(*barriers));
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if (!barriers)
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return -1;
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/* Used for synchronization between two threads */
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for (i = 0; i < nr; i++)
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pthread_barrier_init(&barriers[i], NULL, 2);
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ctx.notify = barriers;
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return 0;
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}
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static void htab_mem_bench_exit_barriers(void)
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{
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unsigned int i, nr;
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if (!ctx.notify)
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return;
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nr = (env.producer_cnt + 1) / 2;
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for (i = 0; i < nr; i++)
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pthread_barrier_destroy(&ctx.notify[i]);
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free(ctx.notify);
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}
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static const struct htab_mem_use_case *htab_mem_find_use_case_or_exit(const char *name)
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{
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unsigned int i;
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for (i = 0; i < ARRAY_SIZE(use_cases); i++) {
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if (!strcmp(name, use_cases[i].name))
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return &use_cases[i];
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}
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fprintf(stderr, "no such use-case: %s\n", name);
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fprintf(stderr, "available use case:");
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for (i = 0; i < ARRAY_SIZE(use_cases); i++)
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fprintf(stderr, " %s", use_cases[i].name);
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fprintf(stderr, "\n");
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exit(1);
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}
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static void htab_mem_setup_impl(enum bpf_map_type map_type)
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{
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struct bpf_map *map;
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const char **names;
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int err;
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setup_libbpf();
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ctx.uc = htab_mem_find_use_case_or_exit(args.use_case);
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err = htab_mem_bench_init_barriers();
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if (err) {
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fprintf(stderr, "failed to init barrier\n");
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exit(1);
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}
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ctx.fd = cgroup_setup_and_join("/htab_mem");
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if (ctx.fd < 0)
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goto cleanup;
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ctx.skel = htab_mem_bench__open();
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if (!ctx.skel) {
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fprintf(stderr, "failed to open skeleton\n");
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goto cleanup;
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}
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map = ctx.skel->maps.htab;
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bpf_map__set_type(map, map_type);
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bpf_map__set_value_size(map, args.value_size);
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/* Ensure that different CPUs can operate on different subset */
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bpf_map__set_max_entries(map, MAX(8192, 64 * env.nr_cpus));
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if (map_type != BPF_MAP_TYPE_RHASH && args.preallocated)
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bpf_map__set_map_flags(map, bpf_map__map_flags(map) & ~BPF_F_NO_PREALLOC);
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names = ctx.uc->progs;
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while (*names) {
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struct bpf_program *prog;
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prog = bpf_object__find_program_by_name(ctx.skel->obj, *names);
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if (!prog) {
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fprintf(stderr, "no such program %s\n", *names);
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goto cleanup;
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}
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bpf_program__set_autoload(prog, true);
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names++;
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}
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ctx.skel->bss->nr_thread = env.producer_cnt;
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err = htab_mem_bench__load(ctx.skel);
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if (err) {
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fprintf(stderr, "failed to load skeleton\n");
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goto cleanup;
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}
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err = htab_mem_bench__attach(ctx.skel);
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if (err) {
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fprintf(stderr, "failed to attach skeleton\n");
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goto cleanup;
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}
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return;
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cleanup:
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htab_mem_bench__destroy(ctx.skel);
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htab_mem_bench_exit_barriers();
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if (ctx.fd >= 0) {
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close(ctx.fd);
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cleanup_cgroup_environment();
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}
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exit(1);
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}
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static void htab_mem_setup(void)
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{
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htab_mem_setup_impl(BPF_MAP_TYPE_HASH);
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}
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static void rhtab_mem_setup(void)
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{
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htab_mem_setup_impl(BPF_MAP_TYPE_RHASH);
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}
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static void htab_mem_add_fn(pthread_barrier_t *notify)
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{
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while (true) {
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/* Do addition */
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(void)syscall(__NR_getpgid, 0);
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/* Notify deletion thread to do deletion */
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pthread_barrier_wait(notify);
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/* Wait for deletion to complete */
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pthread_barrier_wait(notify);
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}
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}
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static void htab_mem_delete_fn(pthread_barrier_t *notify)
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{
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while (true) {
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/* Wait for addition to complete */
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pthread_barrier_wait(notify);
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/* Do deletion */
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(void)syscall(__NR_getppid);
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/* Notify addition thread to do addition */
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pthread_barrier_wait(notify);
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}
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}
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static void *htab_mem_producer(void *arg)
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{
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pthread_barrier_t *notify;
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int seq;
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if (!ctx.uc->need_sync) {
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while (true)
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(void)syscall(__NR_getpgid, 0);
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return NULL;
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}
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seq = (long)arg;
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notify = &ctx.notify[seq / 2];
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if (seq & 1)
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htab_mem_delete_fn(notify);
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else
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htab_mem_add_fn(notify);
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return NULL;
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}
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static void htab_mem_read_mem_cgrp_file(const char *name, unsigned long *value)
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{
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char buf[32];
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ssize_t got;
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int fd;
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fd = openat(ctx.fd, name, O_RDONLY);
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if (fd < 0) {
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/* cgroup v1 ? */
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fprintf(stderr, "no %s\n", name);
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*value = 0;
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return;
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}
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got = read(fd, buf, sizeof(buf) - 1);
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close(fd);
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if (got <= 0) {
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*value = 0;
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return;
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}
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buf[got] = 0;
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*value = strtoull(buf, NULL, 0);
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}
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static void htab_mem_measure(struct bench_res *res)
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{
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res->hits = atomic_swap(&ctx.skel->bss->op_cnt, 0) / env.producer_cnt;
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htab_mem_read_mem_cgrp_file("memory.current", &res->gp_ct);
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}
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static void htab_mem_report_progress(int iter, struct bench_res *res, long delta_ns)
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{
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double loop, mem;
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loop = res->hits / 1000.0 / (delta_ns / 1000000000.0);
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mem = res->gp_ct / 1048576.0;
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printf("Iter %3d (%7.3lfus): ", iter, (delta_ns - 1000000000) / 1000.0);
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printf("per-prod-op %7.2lfk/s, memory usage %7.2lfMiB\n", loop, mem);
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}
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static void htab_mem_report_final(struct bench_res res[], int res_cnt)
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{
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double mem_mean = 0.0, mem_stddev = 0.0;
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double loop_mean = 0.0, loop_stddev = 0.0;
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unsigned long peak_mem;
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int i;
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for (i = 0; i < res_cnt; i++) {
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loop_mean += res[i].hits / 1000.0 / (0.0 + res_cnt);
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mem_mean += res[i].gp_ct / 1048576.0 / (0.0 + res_cnt);
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}
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if (res_cnt > 1) {
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for (i = 0; i < res_cnt; i++) {
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loop_stddev += (loop_mean - res[i].hits / 1000.0) *
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(loop_mean - res[i].hits / 1000.0) /
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(res_cnt - 1.0);
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mem_stddev += (mem_mean - res[i].gp_ct / 1048576.0) *
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(mem_mean - res[i].gp_ct / 1048576.0) /
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(res_cnt - 1.0);
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}
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loop_stddev = sqrt(loop_stddev);
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mem_stddev = sqrt(mem_stddev);
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}
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htab_mem_read_mem_cgrp_file("memory.peak", &peak_mem);
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printf("Summary: per-prod-op %7.2lf \u00B1 %7.2lfk/s, memory usage %7.2lf \u00B1 %7.2lfMiB,"
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" peak memory usage %7.2lfMiB\n",
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loop_mean, loop_stddev, mem_mean, mem_stddev, peak_mem / 1048576.0);
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close(ctx.fd);
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cleanup_cgroup_environment();
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}
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static void rhtab_mem_validate(void)
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{
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if (args.preallocated) {
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fprintf(stderr, "rhash map does not support preallocation\n");
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exit(1);
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}
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htab_mem_validate();
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}
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const struct bench bench_htab_mem = {
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.name = "htab-mem",
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.argp = &bench_htab_mem_argp,
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.validate = htab_mem_validate,
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.setup = htab_mem_setup,
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.producer_thread = htab_mem_producer,
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.measure = htab_mem_measure,
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.report_progress = htab_mem_report_progress,
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.report_final = htab_mem_report_final,
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};
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const struct bench bench_rhtab_mem = {
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.name = "rhtab-mem",
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.argp = &bench_htab_mem_argp,
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.validate = rhtab_mem_validate,
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.setup = rhtab_mem_setup,
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.producer_thread = htab_mem_producer,
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.measure = htab_mem_measure,
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.report_progress = htab_mem_report_progress,
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.report_final = htab_mem_report_final,
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};
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