C++执行内存memcpy的效率测试

在进行memcpy操作时,虽然是内存操作,但是仍然是耗一点点CPU的,今天测试了一下单线程中执行memcpy的效率,这个结果对于配置TCP epoll中的work thread 数量有指导意义。如下基于8K的内存快执行memcpy, 1个线程大约1S能够拷贝500M,如果服务器带宽或网卡到上限是1G,那么网络io的work thread 开2个即可,考虑到消息的解析损耗,3个线程足以抗住硬件的最高负载。 在我到测试机器上到测试结果是:

Intel(R) Xeon(R) CPU           E5405  @ 2.00GHz
do memcpy speed:12.27 ms/MB
each thread can do memcpy 667.645 MB
#include <iostream>
#include <sys/time.h>
#include <string.h>

using namespace std;

int main(int argc, char* argv[])
{
    long len = 8192;
    int  loop = 200;
    char* p = new char[len];
    char* q = p;
    struct timeval start, end;
    gettimeofday(&start, NULL);
    for (int i =0; i < loop; ++i)
    {
            char* p = new char[len];
            *p = char(i);
            memcpy(p, q, len);
            delete [] p;
    }
    gettimeofday(&end, NULL);
    cout <<"do memcpy speed:" << ((end.tv_sec - start.tv_sec)*1000 + double(end.tv_usec - start.tv_usec) / (len*loop/1000/1000) ) / loop<<" ms/MB\n";
    cout <<"each thread can do memcpy "<< double(len)*loop/1000/1000 / ((end.tv_sec - start.tv_sec) + double(end.tv_usec - start.tv_usec) / 1000/1000) <<" MB\n";

}