Linux下测试SSD硬盘读写速率

硬盘分为机械硬盘HDD和固态硬盘SSD两种。现在固态硬盘已经是大势所趋咯。SSD用的接口是NVME。在NVME协议下面还有一层PCIe协议。HDD硬盘接口有SATA，SATA接口常用的工作模式有AHCI。SATA硬盘接口最大速率是600MBytes/s。接下来我通过C代码测试SSD的读写性能。

代码采用的是直接IO方式，这个测的速率不加直接IO的四倍。
test_ssd.c
#define _GNU_SOURCE
#include<stdio.h>
#include <time.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
//#include <unistd.h> /* add r/w include is error */

void print_usage(char *file)
{
printf("Usage:\n");
printf("%s <filename> <cnt> <ONCE_SIZE> <r/w>\n", file);
}

int main(int argc, char **argv)
{
time_t Time_Start,Time_End;

double run_time = 0;

char* realbuff = NULL;

int fd,i,cnt,block_size,szie;
int pagesize,error,flags;

if( argc!=5)
{
print_usage(argv[0]);
return(-1);
}

if('r' == argv[4][0])
{
printf("running read operations....\n");
flags = 0;
}
else if('w' == argv[4][0]){
printf("running write operations....\n");
flags = 1;
}
else{
printf("r/w error\n");
return -1;
}

fd = open(argv[1], O_CREAT | O_RDWR| O_DIRECT);
if(fd <0){
printf("open is fail\n");
return-1;
}

pagesize=getpagesize();
cnt = strtoul (argv[2], NULL, 0);
szie = strtoul (argv[3], NULL, 0);
block_size = (1024*1024*szie);
realbuff = malloc(block_size+pagesize);
if(realbuff ==NULL){
printf("malloc realbuff is fail\n");
return -1;
}
char *alignedbuff = (char*)((((unsigned int ) realbuff+pagesize-1)/pagesize)*pagesize);
memset(alignedbuff,argv[1][1],block_size);

if(1 == flags){
Time_Start = clock();
for(i=0;i<cnt;i++){
error = write(fd, alignedbuff, block_size);
if(error <=0)
{
perror("error:");
printf("write is fail\n");
free(realbuff);
return -1;
}
}
//printf("%d %s %s\n",__LINE__,__FUNCTION__,__FILE__);

Time_End = clock();
run_time = (double)(Time_End-Time_Start)/CLOCKS_PER_SEC;
printf( "write %d M cost times:%f s\n",(szie*cnt),run_time);
}
else{
Time_Start = clock();
for(i=0;i<cnt;i++){
error = read(fd, alignedbuff, block_size);
if(error <=0)
{
perror("error:");
printf("write is fail\n");
free(realbuff);
return -1;
}
}

Time_End = clock();
run_time = (double)(Time_End-Time_Start)/CLOCKS_PER_SEC;
printf( "read %d M cost times:%f s\n",(szie*cnt),run_time);
}

free(realbuff);
close(fd);
return 0;
}

代码中红色部分需要注意，不能添加这个头文件，不然会出现读写错误，可能是这个头文件下面的write和系统调用不一样。没有去追究原因。测试结果如下：



将clock()函数更改为如下：
#include <sys/time.h>
long  get_ms()
{
struct timeval t;
long tick;
gettimeofday(&t,0);
tick=(long)(t.tv_sec)*1000+(long)(t.tv_usec)/1000;
return tick;
}

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