From e3edfdec04d43aa6276db639d3721e073161d2c2 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Wed, 6 Apr 2016 18:43:31 -0700 Subject: samples/bpf: add tracepoint vs kprobe performance tests the first microbenchmark does fd=open("/proc/self/comm"); for() { write(fd, "test"); } and on 4 cpus in parallel: writes per sec base (no tracepoints, no kprobes) 930k with kprobe at __set_task_comm() 420k with tracepoint at task:task_rename 730k For kprobe + full bpf program manully fetches oldcomm, newcomm via bpf_probe_read. For tracepint bpf program does nothing, since arguments are copied by tracepoint. 2nd microbenchmark does: fd=open("/dev/urandom"); for() { read(fd, buf); } and on 4 cpus in parallel: reads per sec base (no tracepoints, no kprobes) 300k with kprobe at urandom_read() 279k with tracepoint at random:urandom_read 290k bpf progs attached to kprobe and tracepoint are noop. Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- samples/bpf/test_overhead_user.c | 162 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 162 insertions(+) create mode 100644 samples/bpf/test_overhead_user.c (limited to 'samples/bpf/test_overhead_user.c') diff --git a/samples/bpf/test_overhead_user.c b/samples/bpf/test_overhead_user.c new file mode 100644 index 000000000000..d291167fd3c7 --- /dev/null +++ b/samples/bpf/test_overhead_user.c @@ -0,0 +1,162 @@ +/* Copyright (c) 2016 Facebook + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "libbpf.h" +#include "bpf_load.h" + +#define MAX_CNT 1000000 + +static __u64 time_get_ns(void) +{ + struct timespec ts; + + clock_gettime(CLOCK_MONOTONIC, &ts); + return ts.tv_sec * 1000000000ull + ts.tv_nsec; +} + +static void test_task_rename(int cpu) +{ + __u64 start_time; + char buf[] = "test\n"; + int i, fd; + + fd = open("/proc/self/comm", O_WRONLY|O_TRUNC); + if (fd < 0) { + printf("couldn't open /proc\n"); + exit(1); + } + start_time = time_get_ns(); + for (i = 0; i < MAX_CNT; i++) + write(fd, buf, sizeof(buf)); + printf("task_rename:%d: %lld events per sec\n", + cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time)); + close(fd); +} + +static void test_urandom_read(int cpu) +{ + __u64 start_time; + char buf[4]; + int i, fd; + + fd = open("/dev/urandom", O_RDONLY); + if (fd < 0) { + printf("couldn't open /dev/urandom\n"); + exit(1); + } + start_time = time_get_ns(); + for (i = 0; i < MAX_CNT; i++) + read(fd, buf, sizeof(buf)); + printf("urandom_read:%d: %lld events per sec\n", + cpu, MAX_CNT * 1000000000ll / (time_get_ns() - start_time)); + close(fd); +} + +static void loop(int cpu, int flags) +{ + cpu_set_t cpuset; + + CPU_ZERO(&cpuset); + CPU_SET(cpu, &cpuset); + sched_setaffinity(0, sizeof(cpuset), &cpuset); + + if (flags & 1) + test_task_rename(cpu); + if (flags & 2) + test_urandom_read(cpu); +} + +static void run_perf_test(int tasks, int flags) +{ + pid_t pid[tasks]; + int i; + + for (i = 0; i < tasks; i++) { + pid[i] = fork(); + if (pid[i] == 0) { + loop(i, flags); + exit(0); + } else if (pid[i] == -1) { + printf("couldn't spawn #%d process\n", i); + exit(1); + } + } + for (i = 0; i < tasks; i++) { + int status; + + assert(waitpid(pid[i], &status, 0) == pid[i]); + assert(status == 0); + } +} + +static void unload_progs(void) +{ + close(prog_fd[0]); + close(prog_fd[1]); + close(event_fd[0]); + close(event_fd[1]); +} + +int main(int argc, char **argv) +{ + struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY}; + char filename[256]; + int num_cpu = 8; + int test_flags = ~0; + + setrlimit(RLIMIT_MEMLOCK, &r); + + if (argc > 1) + test_flags = atoi(argv[1]) ? : test_flags; + if (argc > 2) + num_cpu = atoi(argv[2]) ? : num_cpu; + + if (test_flags & 0x3) { + printf("BASE\n"); + run_perf_test(num_cpu, test_flags); + } + + if (test_flags & 0xC) { + snprintf(filename, sizeof(filename), + "%s_kprobe_kern.o", argv[0]); + if (load_bpf_file(filename)) { + printf("%s", bpf_log_buf); + return 1; + } + printf("w/KPROBE\n"); + run_perf_test(num_cpu, test_flags >> 2); + unload_progs(); + } + + if (test_flags & 0x30) { + snprintf(filename, sizeof(filename), + "%s_tp_kern.o", argv[0]); + if (load_bpf_file(filename)) { + printf("%s", bpf_log_buf); + return 1; + } + printf("w/TRACEPOINT\n"); + run_perf_test(num_cpu, test_flags >> 4); + unload_progs(); + } + + return 0; +} -- cgit v1.2.3