程序员练级攻略：Linux系统、内存和网络-[2026重制版]

// 内存屏障示例：生产者-消费者模型
#include <stdatomic.h>
#include <pthread.h>

atomic_int data_ready = 0;
int shared_data = 0;

void* producer(void* arg) {
    // 1. 准备数据
    shared_data = 42;

    // 2. 内存屏障：确保shared_data的写入对所有线程可见
    atomic_store_explicit(&data_ready, 1, memory_order_release);

    return NULL;
}

void* consumer(void* arg) {
    // 1. 等待数据就绪（带获取语义）
    while (!atomic_load_explicit(&data_ready, memory_order_acquire)) {
        // busy wait 或 sched_yield()
    }

    // 2. 此时shared_data一定可见且正确
    printf("Data: %d\n", shared_data);  // 一定是42

    return NULL;
}

# /etc/sysctl.conf 关键参数

# === TCP缓冲区调整 ===
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_wmem = 4096 65536 16777216

# === TCP连接优化 ===
net.ipv4.tcp_fin_timeout = 15
net.ipv4.tcp_keepalive_time = 300
net.ipv4.tcp_keepalive_intvl = 30
net.ipv4.tcp_keepalive_probes = 5
net.ipv4.tcp_max_syn_backlog = 8192
net.ipv4.tcp_tw_reuse = 1

# === TCP拥塞控制 ===
# 可选: cubic (默认), bbr, htcp, vegas
net.ipv4.tcp_congestion_control = bbr   # Google BBR算法

# === 队列长度 ===
net.core.somaxconn = 65535
net.core.netdev_max_backlog = 5000

# === 文件描述符 ===
fs.file-max = 1048576
net.ipv4.ip_local_port_range = 1024 65535

// hello_ebp.c - 一个简单的eBPF程序：跟踪进程exec
// （以libbpf/BCC风格宏的伪代码示意，实际API因工具链版本而异）
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>

struct event_t {
    u32 pid;
    char comm[TASK_COMM_LEN];
};

// 定义BPF映射表，用户态读取
BPF_MAP_DEF(events_map, PERCPU_ARRAY, u64, struct event_t, 256);

SEC("tracepoint/syscalls/sys_enter_execve")
int trace_exec(void *ctx)
{
    struct event_t event = {};
    u64 id = bpf_get_current_pid_tgid();
    event.pid = id >> 32;  // 高32位是PID
    bpf_get_current_comm(&event.comm, sizeof(event.comm));

    // 写入映射表
    u64 index = bpf_get_smp_processor_id();
    bpf_map_update_elem(&events_map, &index, &event, BPF_ANY);

    return 0;
}

char LICENSE[] SEC("license") = "GPL";