The Linux kernel caches read/write access to disk in order to improve performance. The code sample below shows an example of this.
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
int
main()
{
int fd = open("./test.txt", O_RDWR, 0766);
if (fd < 0) {
printf("open file failed %d\n", errno);
return -1;
}
char msg[100] = "write this msg to disk";
write(fd, msg, strlen(msg));
return 0;
}
I would like to know: is the copying of the msg to the buffer a time-consuming operation?