linux下锁/无锁性能比较

2017-01-14 08:48:55来源:CSDN作者:innobase人点击

代码示例中三种类型:        1.pthread_mutex_t,互斥锁        2.__sync_add_and_fetch,GCC自带的原子锁        3.nolock,无锁方式
代码如下:/*************************************************************************        > File Name: log_test.c        > Author: perrynzhou        > Mail: 715169549@qq.com        > Created Time: Fri 13 Jan 2017 05:00:46 PM HKT ************************************************************************/#include <stdio.h>#include <stdint.h>#include <pthread.h>#include <stdbool.h>#include <time.h>#define MAX_THD_SIZE 2048uint64_t max = 0;uint64_t sum = 0;pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;static void incrment_with_lock (int *data){        uint64_t i = 0;        uint64_t count = max / MAX_THD_SIZE;        for (; i < count; i++)        {                pthread_mutex_lock (&lock);                (*data)++;                pthread_mutex_unlock (&lock);        }}static void incrment_with_nolock (int *data){        uint64_t i = 0;        uint64_t count = max / MAX_THD_SIZE;        for (; i < count; i++)        {                (*data)++;        }}static void incrment_with_atomic (int *data){        uint64_t i = 0;        uint64_t count = max / MAX_THD_SIZE;        for (; i < count; i++)        {                __sync_add_and_fetch (data, 1);        }}bool is_digit (const char *s){        if (s == NULL)        {                return false;        }        while (*s != '/0')        {                if (isdigit (*(s++)) == 0)                {                        return false;                }        }        return true;}int main (int argc, char *argv[]){        if (argc != 2 || !is_digit (argv[1]))        {                fprintf (stdout, "usage: %s number /n", argv[0]);                return 0;        }        max = atoi (argv[1]);        clock_t start, end;        start = clock ();        pthread_t thd[MAX_THD_SIZE];        uint32_t i = 0;#ifdef LOCK        for (; i < MAX_THD_SIZE; i++)        {                pthread_create (&thd[i], NULL, (void *) &incrment_with_lock, (void *) &sum);        }        for (i = 0; i < MAX_THD_SIZE; i++)        {                pthread_join (thd[i], NULL);        }        end = clock ();        fprintf (stdout, "sum = %d,incremnt_with_lock run time :%f s/n", sum, (double) (end - start) / CLOCKS_PER_SEC);#endif#ifdef ATOMIC        for (; i < MAX_THD_SIZE; i++)        {                pthread_create (&thd[i], NULL, (void *) &incrment_with_atomic, (void *) &sum);        }        for (i = 0; i < MAX_THD_SIZE; i++)        {                pthread_join (thd[i], NULL);        }        end = clock ();        fprintf (stdout, "sum = %d,incremnt_with_atomic run time :%f s/n", sum, (double) (end - start) / CLOCKS_PER_SEC);#endif#ifdef NOLOCK        for (; i < MAX_THD_SIZE; i++)        {                pthread_create (&thd[i], NULL, (void *) &incrment_with_nolock, (void *) &sum);        }        for (i = 0; i < MAX_THD_SIZE; i++)        {                pthread_join (thd[i], NULL);        }        end = clock ();        fprintf (stdout, "sum = %d,incremnt_with_nolock run time :%f s/n", sum, (double) (end - start) / CLOCKS_PER_SEC);#endif        return 0;}

测试结果:
这里写图片描述

结果描述    1.使用pthread_mutex_xxx类似的函数,针对多线程中操作一个变量,代价挺高,性能比较低。    2.不加锁这总方式,数据或错乱,但是性能是最佳的。    3.使用GCC原子锁,有一定的开销但是代价比使用pthread_mutex_xxx函数小。

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