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This benchmark measures grace period latency and kthread cpu usage of RCU Tasks Trace when many processes are creating/deleting BPF local_storage. Intent here is to quantify improvement on these metrics after Paul's recent RCU Tasks patches [0]. Specifically, fork 15k tasks which call a bpf prog that creates/destroys task local_storage and sleep in a loop, resulting in many call_rcu_tasks_trace calls. To determine grace period latency, trace time elapsed between rcu_tasks_trace_pregp_step and rcu_tasks_trace_postgp; for cpu usage look at rcu_task_trace_kthread's stime in /proc/PID/stat. On my virtualized test environment (Skylake, 8 cpus) benchmark results demonstrate significant improvement: BEFORE Paul's patches: SUMMARY tasks_trace grace period latency avg 22298.551 us stddev 1302.165 us SUMMARY ticks per tasks_trace grace period avg 2.291 stddev 0.324 AFTER Paul's patches: SUMMARY tasks_trace grace period latency avg 16969.197 us stddev 2525.053 us SUMMARY ticks per tasks_trace grace period avg 1.146 stddev 0.178 Note that since these patches are not in bpf-next benchmarking was done by cherry-picking this patch onto rcu tree. [0] https://lore.kernel.org/rcu/20220620225402.GA3842369@paulmck-ThinkPad-P17-Gen-1/ Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Paul E. McKenney <paulmck@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20220705190018.3239050-1-davemarchevsky@fb.com
103 lines
2.5 KiB
C
103 lines
2.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#pragma once
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#include <stdlib.h>
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#include <stdbool.h>
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#include <linux/err.h>
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#include <errno.h>
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#include <unistd.h>
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#include <bpf/bpf.h>
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#include <bpf/libbpf.h>
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#include <math.h>
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#include <time.h>
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#include <sys/syscall.h>
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struct cpu_set {
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bool *cpus;
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int cpus_len;
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int next_cpu;
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};
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struct env {
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char *bench_name;
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int duration_sec;
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int warmup_sec;
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bool verbose;
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bool list;
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bool affinity;
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int consumer_cnt;
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int producer_cnt;
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struct cpu_set prod_cpus;
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struct cpu_set cons_cpus;
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};
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struct basic_stats {
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double mean;
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double stddev;
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};
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struct bench_res {
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long hits;
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long drops;
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long false_hits;
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long important_hits;
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unsigned long gp_ns;
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unsigned long gp_ct;
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unsigned int stime;
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};
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struct bench {
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const char *name;
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void (*validate)(void);
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void (*setup)(void);
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void *(*producer_thread)(void *ctx);
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void *(*consumer_thread)(void *ctx);
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void (*measure)(struct bench_res* res);
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void (*report_progress)(int iter, struct bench_res* res, long delta_ns);
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void (*report_final)(struct bench_res res[], int res_cnt);
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};
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struct counter {
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long value;
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} __attribute__((aligned(128)));
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extern struct env env;
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extern const struct bench *bench;
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void setup_libbpf(void);
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void hits_drops_report_progress(int iter, struct bench_res *res, long delta_ns);
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void hits_drops_report_final(struct bench_res res[], int res_cnt);
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void false_hits_report_progress(int iter, struct bench_res *res, long delta_ns);
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void false_hits_report_final(struct bench_res res[], int res_cnt);
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void ops_report_progress(int iter, struct bench_res *res, long delta_ns);
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void ops_report_final(struct bench_res res[], int res_cnt);
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void local_storage_report_progress(int iter, struct bench_res *res,
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long delta_ns);
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void local_storage_report_final(struct bench_res res[], int res_cnt);
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void grace_period_latency_basic_stats(struct bench_res res[], int res_cnt,
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struct basic_stats *gp_stat);
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void grace_period_ticks_basic_stats(struct bench_res res[], int res_cnt,
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struct basic_stats *gp_stat);
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static inline __u64 get_time_ns(void)
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{
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struct timespec t;
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clock_gettime(CLOCK_MONOTONIC, &t);
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return (u64)t.tv_sec * 1000000000 + t.tv_nsec;
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}
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static inline void atomic_inc(long *value)
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{
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(void)__atomic_add_fetch(value, 1, __ATOMIC_RELAXED);
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}
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static inline void atomic_add(long *value, long n)
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{
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(void)__atomic_add_fetch(value, n, __ATOMIC_RELAXED);
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}
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static inline long atomic_swap(long *value, long n)
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{
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return __atomic_exchange_n(value, n, __ATOMIC_RELAXED);
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}
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