cregit-Linux how code gets into the kernel

Release 4.10 samples/bpf/test_overhead_user.c

Directory: samples/bpf
/* 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 <sched.h>
#include <stdio.h>
#include <sys/types.h>
#include <asm/unistd.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <signal.h>
#include <linux/bpf.h>
#include <string.h>
#include <time.h>
#include <sys/resource.h>
#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; }

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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); }

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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); }

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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); }

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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); } }

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static void unload_progs(void) { close(prog_fd[0]); close(prog_fd[1]); close(event_fd[0]); close(event_fd[1]); }

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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; }

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Directory: samples/bpf
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