Hi,

I'm writing a program comparing file access patterns. I'm starting with
'read' on a 3MB file.

The function that reads from the file is the following:

void read1test(int fd, void * buffer) {
ssize_t bytesr;

bytesr = read(fd, buffer, BUFFSIZE1);
if (bytesr < 0) {
perror("read:");
exit(bytesr);
}
}

Using Eclipse+CDT, I'm debugging the code, and when the execution is at
the bytesr = read() line, I am not able to see what is stored in the
'buffer' variable.

Below you can see part of the code.

Thanks in advance,

FBM
 ________________________________________
__________________________
#define BUFFSIZE1 1024
#define FOR_READING 0 //(of no use)

#include <fcntl.h>
#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

double now(void) {
struct timeval t;
gettimeofday(&t,NULL);
return ((double)t.tv_sec + (double)t.tv_usec/1000000.0);
}

int openRtest(char *pathnameX) {
int fd;
fd = open(pathnameX, O_RDONLY);
if (fd < 0) {
perror("desc:");
exit(fd);
}
return fd;
}

int openWtest(char *pathnameX) {
int fd;
fd = open(pathnameX, O_RDWR|O_CREAT|S_IRUSR|S_IWUSR);
if (fd < 0) {
perror("desc:");
exit(fd);
}
return fd;
}

void read1test(int fd, void * buffer) {
ssize_t bytesr;

bytesr = read(fd, buffer, BUFFSIZE1);
if (bytesr < 0) {
perror("read:");
exit(bytesr);
}
}

void lseek1test(int fd, off_t offset, int lseekaction, void * buffer,
int seekcurr) {
int currpos, nextposition;
ssize_t bytesr;


currpos = lseek(fd, 0, seekcurr);
if (currpos == -1) {
perror("lseek:");
exit(currpos);
}
switch (lseekaction) {
case 0:
while (bytesr != 0) {
bytesr = read(fd, buffer, BUFFSIZE1);
if (bytesr < 0) {
perror("read:");
exit(bytesr);
}
nextposition = lseek(fd, offset, SEEK_CUR);
}
}
}

void write1test(int fd, void *buffer) {

ssize_t bytesw;
size_t nbytes;
bytesw = write(fd, buffer, nbytes);
if (bytesw < 0) {
perror("write:");
exit(bytesw);
}

}
int main(int argc, char** argv) {
int fdo1, fdo2, fdo3, initposition;
double t;
char * pathname1, * pathname2;
void * bufread , * bufread2;
char outputpathname[] = "/tmp/output1.txt";

initposition = 0;

bufread = (void*)malloc(BUFFSIZE1*sizeof(void));
bufread2 = (void*)malloc(BUFFSIZE1*sizeof(void));
pathname1 = argv[1];
pathname2 = argv[2];

/* opening file 1 test	*/
t = now();
fdo1 = openRtest(pathname1);
t = now() - t;
printf("time to open file %s: %.3f\n", pathname1, t);

/* opening file 2 test	*/
t = now();
fdo2 = openRtest(pathname2);
t = now() - t;
printf("time to open file %s: %.3f\n", pathname2, t);


t = now();
read1test(fdo1, bufread);
t = now() - t;
printf("time to read blocksize %d from file %s: %.3f\n", BUFFSIZE1,
pathname1, t);

t = now();
read1test(fdo2, bufread);
t = now() - t;
printf("time to read blocksize %d from file %s: %.3f\n", BUFFSIZE1,
pathname2, t);

(........)

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About post:

I can see the output with printf(buffer)... so, I guess it's not a
problem.. though I don't understand why it doesn't appear in the
debugger..

Anyway, thanks

FBM

ferbar wrote:
> Hi,
>
> I'm writing a program comparing file access patterns. I'm starting with
> 'read' on a 3MB file.
>
> The function that reads from the file is the following:
>
> void read1test(int fd, void * buffer) {
> 	ssize_t bytesr;
>
> 	bytesr = read(fd, buffer, BUFFSIZE1);
> 	if (bytesr < 0) {
> 		perror("read:");
> 		exit(bytesr);
> 	}
> }
>
> Using Eclipse+CDT, I'm debugging the code, and when the execution is at
> the bytesr = read() line, I am not able to see what is stored in the
> 'buffer' variable.
>
> Below you can see part of the code.
>
> Thanks in advance,
>
> FBM
>  ________________________________________
__________________________
> #define BUFFSIZE1 1024
> #define FOR_READING 0 //(of no use)
>
> #include <fcntl.h>
> #include <sys/time.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <unistd.h>
>
> double now(void) {
> 	struct timeval t;
> 	gettimeofday(&t,NULL);
> 	return ((double)t.tv_sec + (double)t.tv_usec/1000000.0);
> }
>
> int openRtest(char *pathnameX) {
> 	int fd;
> 	fd = open(pathnameX, O_RDONLY);
> 	if (fd < 0) {
> 		perror("desc:");
> 		exit(fd);
> 	}
> 	return fd;
> }
>
> int openWtest(char *pathnameX) {
> 	int fd;
> 	fd = open(pathnameX, O_RDWR|O_CREAT|S_IRUSR|S_IWUSR);
> 	if (fd < 0) {
> 		perror("desc:");
> 		exit(fd);
> 	}
> 	return fd;
> }
>
> void read1test(int fd, void * buffer) {
> 	ssize_t bytesr;
>
> 	bytesr = read(fd, buffer, BUFFSIZE1);
> 	if (bytesr < 0) {
> 		perror("read:");
> 		exit(bytesr);
> 	}
> }
>
> void lseek1test(int fd, off_t offset, int lseekaction, void * buffer,
> int seekcurr) {
> 	int currpos, nextposition;
> 	ssize_t bytesr;
>
>
> 	currpos = lseek(fd, 0, seekcurr);
> 	if (currpos == -1) {
> 		perror("lseek:");
> 		exit(currpos);
> 	}
> 	switch (lseekaction) {
> 		case 0:
> 			while (bytesr != 0) {
> 				bytesr = read(fd, buffer, BUFFSIZE1);
> 				if (bytesr < 0) {
> 					perror("read:");
> 					exit(bytesr);
> 				}
> 				nextposition = lseek(fd, offset, SEEK_CUR);
> 			}
> 	}
> }
>
> void write1test(int fd, void *buffer) {
>
> 	ssize_t bytesw;
> 	size_t nbytes;
> 	bytesw = write(fd, buffer, nbytes);
> 	if (bytesw < 0) {
> 		perror("write:");
> 		exit(bytesw);
> 	}
>
> }
> int main(int argc, char** argv) {
> 	int fdo1, fdo2, fdo3, initposition;
> 	double t;
> 	char * pathname1, * pathname2;
> 	void * bufread , * bufread2;
> 	char outputpathname[] = "/tmp/output1.txt";
>
> 		initposition = 0;
>
> 		bufread = (void*)malloc(BUFFSIZE1*sizeof(void));
> 		bufread2 = (void*)malloc(BUFFSIZE1*sizeof(void));
> 		pathname1 = argv[1];
> 		pathname2 = argv[2];
>
> 		/* opening file 1 test	*/
> 		t = now();
> 		fdo1 = openRtest(pathname1);
> 		t = now() - t;
> 		printf("time to open file %s: %.3f\n", pathname1, t);
>
> 		/* opening file 2 test	*/
> 		t = now();
> 		fdo2 = openRtest(pathname2);
> 		t = now() - t;
> 		printf("time to open file %s: %.3f\n", pathname2, t);
>
>
> 		t = now();
> 		read1test(fdo1, bufread);
> 		t = now() - t;
> 		printf("time to read blocksize %d from file %s: %.3f\n", BUFFSIZE1,
> pathname1, t);
>
> 		t = now();
> 		read1test(fdo2, bufread);
> 		t = now() - t;
> 		printf("time to read blocksize %d from file %s: %.3f\n", BUFFSIZE1,
> pathname2, t);
>
> (........)

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