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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /tools/testing/selftests/bpf/benchs/bench_local_storage_rcu_tasks_trace.c | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/testing/selftests/bpf/benchs/bench_local_storage_rcu_tasks_trace.c')
-rw-r--r-- | tools/testing/selftests/bpf/benchs/bench_local_storage_rcu_tasks_trace.c | 263 |
1 files changed, 263 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/benchs/bench_local_storage_rcu_tasks_trace.c b/tools/testing/selftests/bpf/benchs/bench_local_storage_rcu_tasks_trace.c new file mode 100644 index 0000000000..edf0b00418 --- /dev/null +++ b/tools/testing/selftests/bpf/benchs/bench_local_storage_rcu_tasks_trace.c @@ -0,0 +1,263 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */ + +#include <argp.h> + +#include <sys/prctl.h> +#include "local_storage_rcu_tasks_trace_bench.skel.h" +#include "bench.h" + +#include <signal.h> + +static struct { + __u32 nr_procs; + __u32 kthread_pid; +} args = { + .nr_procs = 1000, + .kthread_pid = 0, +}; + +enum { + ARG_NR_PROCS = 7000, + ARG_KTHREAD_PID = 7001, +}; + +static const struct argp_option opts[] = { + { "nr_procs", ARG_NR_PROCS, "NR_PROCS", 0, + "Set number of user processes to spin up"}, + { "kthread_pid", ARG_KTHREAD_PID, "PID", 0, + "Pid of rcu_tasks_trace kthread for ticks tracking"}, + {}, +}; + +static error_t parse_arg(int key, char *arg, struct argp_state *state) +{ + long ret; + + switch (key) { + case ARG_NR_PROCS: + ret = strtol(arg, NULL, 10); + if (ret < 1 || ret > UINT_MAX) { + fprintf(stderr, "invalid nr_procs\n"); + argp_usage(state); + } + args.nr_procs = ret; + break; + case ARG_KTHREAD_PID: + ret = strtol(arg, NULL, 10); + if (ret < 1) { + fprintf(stderr, "invalid kthread_pid\n"); + argp_usage(state); + } + args.kthread_pid = ret; + break; +break; + default: + return ARGP_ERR_UNKNOWN; + } + + return 0; +} + +const struct argp bench_local_storage_rcu_tasks_trace_argp = { + .options = opts, + .parser = parse_arg, +}; + +#define MAX_SLEEP_PROCS 150000 + +static void validate(void) +{ + if (env.producer_cnt != 1) { + fprintf(stderr, "benchmark doesn't support multi-producer!\n"); + exit(1); + } + if (env.consumer_cnt != 0) { + fprintf(stderr, "benchmark doesn't support consumer!\n"); + exit(1); + } + + if (args.nr_procs > MAX_SLEEP_PROCS) { + fprintf(stderr, "benchmark supports up to %u sleeper procs!\n", + MAX_SLEEP_PROCS); + exit(1); + } +} + +static long kthread_pid_ticks(void) +{ + char procfs_path[100]; + long stime; + FILE *f; + + if (!args.kthread_pid) + return -1; + + sprintf(procfs_path, "/proc/%u/stat", args.kthread_pid); + f = fopen(procfs_path, "r"); + if (!f) { + fprintf(stderr, "couldn't open %s, exiting\n", procfs_path); + goto err_out; + } + if (fscanf(f, "%*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %ld", &stime) != 1) { + fprintf(stderr, "fscanf of %s failed, exiting\n", procfs_path); + goto err_out; + } + fclose(f); + return stime; + +err_out: + if (f) + fclose(f); + exit(1); + return 0; +} + +static struct { + struct local_storage_rcu_tasks_trace_bench *skel; + long prev_kthread_stime; +} ctx; + +static void sleep_and_loop(void) +{ + while (true) { + sleep(rand() % 4); + syscall(__NR_getpgid); + } +} + +static void local_storage_tasks_trace_setup(void) +{ + int i, err, forkret, runner_pid; + + runner_pid = getpid(); + + for (i = 0; i < args.nr_procs; i++) { + forkret = fork(); + if (forkret < 0) { + fprintf(stderr, "Error forking sleeper proc %u of %u, exiting\n", i, + args.nr_procs); + goto err_out; + } + + if (!forkret) { + err = prctl(PR_SET_PDEATHSIG, SIGKILL); + if (err < 0) { + fprintf(stderr, "prctl failed with err %d, exiting\n", errno); + goto err_out; + } + + if (getppid() != runner_pid) { + fprintf(stderr, "Runner died while spinning up procs, exiting\n"); + goto err_out; + } + sleep_and_loop(); + } + } + printf("Spun up %u procs (our pid %d)\n", args.nr_procs, runner_pid); + + setup_libbpf(); + + ctx.skel = local_storage_rcu_tasks_trace_bench__open_and_load(); + if (!ctx.skel) { + fprintf(stderr, "Error doing open_and_load, exiting\n"); + goto err_out; + } + + ctx.prev_kthread_stime = kthread_pid_ticks(); + + if (!bpf_program__attach(ctx.skel->progs.get_local)) { + fprintf(stderr, "Error attaching bpf program\n"); + goto err_out; + } + + if (!bpf_program__attach(ctx.skel->progs.pregp_step)) { + fprintf(stderr, "Error attaching bpf program\n"); + goto err_out; + } + + if (!bpf_program__attach(ctx.skel->progs.postgp)) { + fprintf(stderr, "Error attaching bpf program\n"); + goto err_out; + } + + return; +err_out: + exit(1); +} + +static void measure(struct bench_res *res) +{ + long ticks; + + res->gp_ct = atomic_swap(&ctx.skel->bss->gp_hits, 0); + res->gp_ns = atomic_swap(&ctx.skel->bss->gp_times, 0); + ticks = kthread_pid_ticks(); + res->stime = ticks - ctx.prev_kthread_stime; + ctx.prev_kthread_stime = ticks; +} + +static void *producer(void *input) +{ + while (true) + syscall(__NR_getpgid); + return NULL; +} + +static void report_progress(int iter, struct bench_res *res, long delta_ns) +{ + if (ctx.skel->bss->unexpected) { + fprintf(stderr, "Error: Unexpected order of bpf prog calls (postgp after pregp)."); + fprintf(stderr, "Data can't be trusted, exiting\n"); + exit(1); + } + + if (env.quiet) + return; + + printf("Iter %d\t avg tasks_trace grace period latency\t%lf ns\n", + iter, res->gp_ns / (double)res->gp_ct); + printf("Iter %d\t avg ticks per tasks_trace grace period\t%lf\n", + iter, res->stime / (double)res->gp_ct); +} + +static void report_final(struct bench_res res[], int res_cnt) +{ + struct basic_stats gp_stat; + + grace_period_latency_basic_stats(res, res_cnt, &gp_stat); + printf("SUMMARY tasks_trace grace period latency"); + printf("\tavg %.3lf us\tstddev %.3lf us\n", gp_stat.mean, gp_stat.stddev); + grace_period_ticks_basic_stats(res, res_cnt, &gp_stat); + printf("SUMMARY ticks per tasks_trace grace period"); + printf("\tavg %.3lf\tstddev %.3lf\n", gp_stat.mean, gp_stat.stddev); +} + +/* local-storage-tasks-trace: Benchmark performance of BPF local_storage's use + * of RCU Tasks-Trace. + * + * Stress RCU Tasks Trace by forking many tasks, all of which do no work aside + * from sleep() loop, and creating/destroying BPF task-local storage on wakeup. + * The number of forked tasks is configurable. + * + * exercising code paths which call call_rcu_tasks_trace while there are many + * thousands of tasks on the system should result in RCU Tasks-Trace having to + * do a noticeable amount of work. + * + * This should be observable by measuring rcu_tasks_trace_kthread CPU usage + * after the grace period has ended, or by measuring grace period latency. + * + * This benchmark uses both approaches, attaching to rcu_tasks_trace_pregp_step + * and rcu_tasks_trace_postgp functions to measure grace period latency and + * using /proc/PID/stat to measure rcu_tasks_trace_kthread kernel ticks + */ +const struct bench bench_local_storage_tasks_trace = { + .name = "local-storage-tasks-trace", + .argp = &bench_local_storage_rcu_tasks_trace_argp, + .validate = validate, + .setup = local_storage_tasks_trace_setup, + .producer_thread = producer, + .measure = measure, + .report_progress = report_progress, + .report_final = report_final, +}; 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