利用可挂载内核模块进行高负载处理

#include  /* for stack_trace_print */#include  /* for module_*, MODULE_*, printk */#include  /* for hrtimer_*, ktime_* */#include  /* for avenrun, LOAD_* */#include  /* for struct task_struct */#include  /* for do_each_thread, while_each_thread */#include "load.h" /* for find_kallsyms_lookup_name */#define BACKTRACE_DEPTH 20 /* 最大栈深度 */void (*ShowStack)(struct task_struct *task, unsigned long *sp, const char *loglvl); /* 将要指向stack_show函数，可以直接输出进程控制块的调用栈 */unsigned int (*StackTraceSaveTask)(struct task_struct *tsk, unsigned long *store, unsigned int size, unsigned int skipnr); /* 将要指向stack_trace_save_tsk */static void print_all_task_stack(void) { /* 打印全部进程调用栈 */    struct task_struct *g, *p; /* 用于遍历进程 */    unsigned long backtrace[BACKTRACE_DEPTH]; /* 用于存储调用栈的函数地址 */    unsigned int nr_bt; /* 用于存储调用栈的层数 */    printk("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!\n");    printk("Load: %lu.%02lu, %lu.%02lu, %lu.%02lu\n", /* 输出近期平均负载 */        LOAD_INT(avenrun[0]), LOAD_FRAC(avenrun[0]),        LOAD_INT(avenrun[1]), LOAD_FRAC(avenrun[1]),        LOAD_INT(avenrun[2]), LOAD_FRAC(avenrun[2]));    rcu_read_lock(); /* 为运行队列上锁 */    printk("dump running task.\n");    do_each_thread(g, p) { /* 遍历运行队列 */        if(p->__state == TASK_RUNNING) {            printk("running task, comm: %s, pid %d\n", p->comm, p->pid);            // show_stack(p, NULL, ""); /* 可以取代下面两个语句 */            nr_bt = StackTraceSaveTask(p, backtrace, BACKTRACE_DEPTH, 0); /* 保存栈 */ // 和下面一个语句一起可以取代上面一条语句            stack_trace_print(backtrace, nr_bt, 0); /* 打印栈 */        }    } while_each_thread(g, p);    printk("dump uninterrupted task.\n");    do_each_thread(g, p) { /* 和上面的遍历类似 */        if(p->__state & TASK_UNINTERRUPTIBLE) {            printk("uninterrupted task, comm: %s, pid %d\n", p->comm, p->pid);            // show_stack(p, NULL, ""); /* 可以取代下面两个语句 */            nr_bt = StackTraceSaveTask(p, backtrace, BACKTRACE_DEPTH, 0); /* 保存栈 */ // 和下面一个语句一起可以取代上面一条语句            stack_trace_print(backtrace, nr_bt, 0); /* 打印栈 */        }    } while_each_thread(g, p);    rcu_read_unlock(); /* 为运行队列解锁 */}struct hrtimer timer; /* 创建一个计时器 */static void check_load(void) { /* 主要的计时器触发后的程序 */    static ktime_t last; /* 默认值是0 */    u64 ms;    int load = LOAD_INT(avenrun[0]);    if(load < 4) /* 近1分钟内平均负载不超过4，没问题 */        return;    ms = ktime_to_ms(ktime_sub(ktime_get(), last)); /* 计算打印栈时间间隔 */    if(ms < 20*1000) /* 打印栈的时间间隔小于20s,不打印 */        return;    last = ktime_get(); /* 获取当前时间 */    print_all_task_stack(); /* 打印全部进程调用栈 */}static enum hrtimer_restart monitor_handler(struct hrtimer *hrtimer) { /* 计时器到期后调用的程序 */    enum hrtimer_restart ret = HRTIMER_RESTART;    check_load();    hrtimer_forward_now(hrtimer, ms_to_ktime(10)); /* 延期10ms后到期 */    return ret;}static void start_timer(void) {    hrtimer_init(&timer, CLOCK_MONOTONIC, HRTIMER_MODE_PINNED); /* 初始化计时器为绑定cpu的自开机以来的恒定时钟 */    timer.function = monitor_handler; /* 设定回调函数 */    hrtimer_start_range_ns(&timer, ms_to_ktime(10), 0, HRTIMER_MODE_REL_PINNED); /* 启动计时器并设定计时模式为绑定cpu的相对时间，计时10ms，松弛范围为0 */}static int load_monitor_init(void) { /* 模块初始化 */    // ShowStack = find_kallsyms_lookup_name("show_stack"); /* 使用show_stack时将此三行取消注释 */    // if(!ShowStack)    //     return -EINVAL;    StackTraceSaveTask = find_kallsyms_lookup_name("stack_trace_save_tsk"); /* 使用stack_trace_save_tsk时将此三行取消注释 */    if(!StackTraceSaveTask)        return -EINVAL;    start_timer();    printk("load-monitor loaded.\n");    return 0;}static void load_monitor_exit(void) { /* 模块退出 */    hrtimer_cancel(&timer); /* 取消计时器 */    printk("load-monitor unloaded.\n");}module_init(load_monitor_init);module_exit(load_monitor_exit);MODULE_DESCRIPTION("load monitor module");MODULE_AUTHOR("Baoyou Xie ");MODULE_LICENSE("GPL");

#include  /* for *kprobe* *//* 调用kprobe找到kallsyms_lookup_name的地址位置 */int noop_pre(struct kprobe *p, struct pt_regs *regs) { return 0; } /* 定义探针前置程序 */void *find_kallsyms_lookup_name(char *sym) { /* 通过kprobe找到函数入口地址 */    int ret;    void *p; /* 用于保存要返回的函数入口地址 */    struct kprobe kp = { /* 初始化探针 */        .symbol_name = sym, /* 设置要跟踪的内核函数名 */        .pre_handler = noop_pre /* 放置前置程序 */    };    if ((ret = register_kprobe(&kp)) < 0) { /* 探针注册失败就报告错误信息并返回空指针 */        printk(KERN_INFO "register_kprobe failed, error\n", ret);        return NULL;    }    /* 保存探针跟踪地址,即函数入口;输出注册成功信息,注销探针,返回地址 */    p = kp.addr;    printk(KERN_INFO "%s addr: %lx\n", sym, (unsigned long)p);    unregister_kprobe(&kp);    return p;}

OS_VER := UNKOWNUNAME := $(shell uname -r)ifneq ($(findstring 4.15.0-39-generic,$(UNAME)),)    OS_VER := UBUNTU_1604endif
ifneq ($(KERNELRELEASE),)    obj-m += $(MODNAME).o    $(MODNAME)-y := main.o    ccflags-y := -I$(PWD)/else    export PWD=`pwd`endif
ifeq ($(KERNEL_BUILD_PATH),)    KERNEL_BUILD_PATH := /lib/modules/`uname -r`/buildendif
ifeq ($(MODNAME),)    export MODNAME=load_monitorendif
all:    make CFLAGS_MODULE=-D$(OS_VER) -C /lib/modules/`uname -r`/build M=`pwd` modulesclean:    make -C $(KERNEL_BUILD_PATH) M=$(PWD) clean