pthread_cond_signal耗时分析

【问题描述】

平均调用要3us

 【内部耗时】

主要是futex_wait系统调用

【ftrace】

参考https://blog.csdn.net/weixin_44410537/article/details/103587609

sudo trace-cmd record -p function_graph -P 25314
sudo trace-cmd report

 【测试代码】

#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<string.h>
#include "sys/time.h"
#include <stdio.h>
#include <pthread.h>
//#define TOTAL_COUNT (1000 * 1000 * 10)
#define TOTAL_COUNT (1000 * 1000 * 10 )
#define NUM_Threads 10
#define COUNT (TOTAL_COUNT/NUM_Threads)
#define PRODUCE_COUNT 18000
#define AVERAGE_PRODUCE_COUNT (PRODUCE_COUNT/NUM_Threads)

#define je_malloc malloc
#define je_free free
//#include <jemalloc/jemalloc.h>
pthread_cond_t  cond;
pthread_mutex_t qlock;

static int producer_index=0;
static int consumer_index=0;
typedef unsigned long long uint64;
#define MIN(A, B)        ((B) < (A) ? (B) : (A))
#define MAX(A, B)        ((B) > (A) ? (B) : (A))

uint64 us_clock_now(){
    struct timeval st;
    gettimeofday(&st, NULL);
    return st.tv_sec * 1000 * 1000 + st.tv_usec;
}

#define TIME_BEGIN(name)  uint64 __##name##begin = us_clock_now();

#define TIME_END(name, print_interval_us) \
do { \
    static __thread uint64 __##name##total = 0; \
    static __thread uint64 __##name##count = 0; \
    static __thread uint64 __##name##min = 1000000000000; \
    static __thread uint64 __##name##max = 0; \
    static __thread uint64 __##name##pre_total = 0; \
    static __thread uint64 __##name##pre_count = 0; \
    static __thread uint64 __##name##log_time = 0;  \
    uint64 current = (us_clock_now() - __##name##begin);\
    __##name##min = MIN(current, __##name##min);        \
    __##name##max = MAX(current, __##name##max);        \
    __##name##total += current; \
    __##name##count++; \
    if (us_clock_now() - __##name##log_time > print_interval_us) \
    { \
        __##name##log_time = us_clock_now(); \
        uint64 __##name##this_total = __##name##total - __##name##pre_total; \
        uint64 __##name##this_count = __##name##count - __##name##pre_count; \
        __##name##pre_total = __##name##total; \
        __##name##pre_count = __##name##count;  \
        if (__##name##this_count > 1)       {                           \
        printf("[TIME=%llu][%ld]%-30s,count:%10llu,avg:%10llu(us), min:%llu,max:%llu, total:%10llu(us)\n", \
            us_clock_now()/1000000,pthread_self(), \
            #name,  __##name##this_count, \
            __##name##this_count == 0 ? 0 :__##name##this_total / __##name##this_count, __##name##min, __##name##max, __##name##this_total); \
        }                                  \
        __##name##min=1000000000000;                    \
        __##name##max = 0;\
    } \
} while (0);

void *PrintHello(void *arg)
{
    printf("producer_begin\n");

    while(1){
        TIME_BEGIN(pthread_cond_signal);
        pthread_cond_signal(&cond);
        TIME_END(pthread_cond_signal, 1000 *1000);
        usleep(1);
    }
    return 0;
}

void *Consumer(void *arg)
{
    printf("Consumer_begin\n");
    while(1){
//        TIME_BEGIN(test_consumer);
        pthread_cond_wait(&cond, &qlock);
//        usleep(10);
//        TIME_END(test_consumer, 1000 *1000);
    }
    return 0;
}


int main(){
    pthread_t producer;
    int i=0;
    int ret = pthread_create(&producer, NULL, PrintHello, (void *)i);
    pthread_t consumer;
    ret = pthread_create(&consumer, NULL, Consumer, (void *)i);
    void *a1;
    pthread_join(producer,&a1);
    return 0;
}