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How to disable the buffer cache of linux fs.

try opening the file with O_DIRECT in the flags. O_DIRECT allows reads and writes to avoid the linux fs cache 舉例; #include s td io.h #include assert.h #include sys/types.h #include sys/stat.h #include fcntl.h unsigned long long get_sys_t
try opening the file with O_DIRECT in the flags.
O_DIRECT allows reads and writes to avoid the linux fs cache

舉例;

#include <stdio.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

unsigned long long get_sys_time();
int main(int argc,char*argv[])
{
int i;
int nRet=0;
if(argc!=3)
{
printf("Usage:pro file size\n");
return 0;
}
unsigned long long llBeg =0;
unsigned long long llEnd =0;
int fp;
int nLen = atoi(argv[2]);

char *pBuf = (char*)calloc(1,nLen);
llBeg = get_sys_time();
fp = open(argv[1],O_RDONLY,O_DIRECT);
assert(fp>0);
memset(pBuf,0,nLen);
nRet = read(fp,pBuf,nLen);
close(fp);
llEnd = get_sys_time();
free(pBuf);
printf("readed=%d\n",nRet);
printf("elapsed time:=%d\n",(llEnd-llBeg)/1000);
return 0;

}


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