Re: [PATCH v2 2/2] selftest/bpf/benchs: Add bpf_map benchmark

[Andrii Nakryiko]

On Tue, May 24, 2022 at 12:53 AM Feng zhou <zhoufeng.zf@xxxxxxxxxxxxx> wrote:
>
> From: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
>
> Add benchmark for hash_map to reproduce the worst case
> that non-stop update when map's free is zero.
>
> Signed-off-by: Feng Zhou <zhoufeng.zf@xxxxxxxxxxxxx>
> ---
>  tools/testing/selftests/bpf/Makefile          |  4 +-
>  tools/testing/selftests/bpf/bench.c           |  2 +
>  .../selftests/bpf/benchs/bench_bpf_map.c      | 78 +++++++++++++++++++
>  .../selftests/bpf/benchs/run_bench_bpf_map.sh | 10 +++
>  .../selftests/bpf/progs/bpf_map_bench.c       | 27 +++++++
>  5 files changed, 120 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/bpf/benchs/bench_bpf_map.c
>  create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_bpf_map.sh
>  create mode 100644 tools/testing/selftests/bpf/progs/bpf_map_bench.c
>

[...]

> +static void setup(void)
> +{
> +       struct bpf_link *link;
> +       int map_fd, i, max_entries;
> +
> +       setup_libbpf();
> +
> +       ctx.skel = bpf_map_bench__open_and_load();
> +       if (!ctx.skel) {
> +               fprintf(stderr, "failed to open skeleton\n");
> +               exit(1);
> +       }
> +
> +       link = bpf_program__attach(ctx.skel->progs.benchmark);
> +       if (!link) {
> +               fprintf(stderr, "failed to attach program!\n");
> +               exit(1);
> +       }
> +
> +       //fill hash_map

don't use C++ comments

> +       map_fd = bpf_map__fd(ctx.skel->maps.hash_map_bench);
> +       max_entries = bpf_map__max_entries(ctx.skel->maps.hash_map_bench);
> +       for (i = 0; i < max_entries; i++)
> +               bpf_map_update_elem(map_fd, &i, &i, BPF_ANY);
> +}
> +
> +const struct bench bench_bpf_map = {
> +       .name = "bpf-map",

this is too generic name, it's testing one particular scenario, so
call this out in the name. bpf-hashmap-full-update or something (same
for all the relevant function and file names)


> +       .validate = validate,
> +       .setup = setup,
> +       .producer_thread = producer,
> +       .consumer_thread = consumer,
> +       .measure = measure,
> +       .report_progress = ops_report_progress,
> +       .report_final = ops_report_final,
> +};
> diff --git a/tools/testing/selftests/bpf/benchs/run_bench_bpf_map.sh b/tools/testing/selftests/bpf/benchs/run_bench_bpf_map.sh
> new file mode 100755
> index 000000000000..d7cc969e4f85
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/benchs/run_bench_bpf_map.sh
> @@ -0,0 +1,10 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +
> +source ./benchs/run_common.sh
> +
> +set -eufo pipefail
> +
> +nr_threads=`expr $(cat /proc/cpuinfo | grep "processor"| wc -l) - 1`
> +summary=$($RUN_BENCH -p $nr_threads bpf-map)
> +printf "$summary"
> diff --git a/tools/testing/selftests/bpf/progs/bpf_map_bench.c b/tools/testing/selftests/bpf/progs/bpf_map_bench.c
> new file mode 100644
> index 000000000000..655366e6e0f4
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/bpf_map_bench.c
> @@ -0,0 +1,27 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2022 Bytedance */
> +
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include "bpf_misc.h"
> +
> +char _license[] SEC("license") = "GPL";
> +
> +#define MAX_ENTRIES 1000
> +
> +struct {
> +       __uint(type, BPF_MAP_TYPE_HASH);
> +       __type(key, u32);
> +       __type(value, u64);
> +       __uint(max_entries, MAX_ENTRIES);
> +} hash_map_bench SEC(".maps");
> +
> +SEC("fentry/" SYS_PREFIX "sys_getpgid")
> +int benchmark(void *ctx)
> +{
> +       u32 key = bpf_get_prandom_u32();
> +       u64 init_val = 1;
> +
> +       bpf_map_update_elem(&hash_map_bench, &key, &init_val, BPF_ANY);
> +       return 0;
> +}
> --
> 2.20.1
>