#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <sys/times.h>
#define MX_BLOCK 8192
#define MN_BLOCK 16
#define FILE_SIZE  1024*2048
#define MX_OUTPUT 32
int main(int argc, char** argv)
{       struct tms ticks;
        char buffer[MX_BLOCK];
        char c = 'a';
        int block_size=MN_BLOCK, nosync[MX_OUTPUT],sync[MX_OUTPUT];
        int v, i, file, num_writes, start, test;
        FILE *data;
        for ( i = 0; i < MX_BLOCK; i++ )
                buffer[i] = c;
        file = open("tester.dat", O_WRONLY | O_CREAT | O_SYNC ,S_IRWXU);
        test=1;
        printf("number of clock ticks per second=%ld", sysconf(_SC_CLK_TCK));
        while (block_size < MX_BLOCK){
	  lseek(file,0,SEEK_SET);
          block_size *= 2;
          num_writes=FILE_SIZE/block_size;
          start=times(&ticks);
          for ( i = 0; i < num_writes; i++ )
                write(file, buffer, block_size);
	  sync[test]=times(&ticks)-start;
          fprintf(stderr,"block size=%d, ticks=%d\n",block_size,sync[test]);
          test++;  
	}
          close(file);
        file = open("tester.dat", O_WRONLY | O_CREAT,S_IRWXU);
        test=1;
        block_size=MN_BLOCK;
        while (block_size < MX_BLOCK){
	  lseek(file,0,SEEK_SET);
          block_size *= 2;
          num_writes=FILE_SIZE/block_size;
          start=times(&ticks);
          for ( i = 0; i < num_writes; i++ )
                write(file, buffer, block_size);
	  nosync[test]=times(&ticks)-start;         
          fprintf(stderr,"block size=%d, ticks=%d\n",block_size,nosync[test]);
          test++;  
	}
          close(file);
	  data=fopen("plot_data","w");
        test=1;
        block_size=MN_BLOCK;
        while (block_size < MX_BLOCK){
          block_size *= 2;
          fprintf(data,"%d %d %d\n",block_size,sync[test],nosync[test]);
          test++; 
	}          
        return 0;
}