Question about a /proc/pid/ctl read

Question

Hi,
I'm trying to read some bytes from /proc/pid/ctl using PCREAD command, I attached a priovec_t struct like this:
     priovec_t strc;
     char buffer[100] = {0};
     strc.pio_offset = atoi(argv[2]);
     strc.pio_len = 100;
     strc.pio_base = buffer;
     long ctrl[2];
     ctrl[0] = PCREAD;
     ctrl[1] = (long)&strc;
     if(write(ctl_fd, ctrl, 2 * sizeof(long)) == -1)
          perror("Read ctl error.");
          close(ctl_fd);
          exit(-1);
but it does not work, so I think the way I pass the perameters may be wrong. I'v search everywhere to get a sample code using /proc file system, but found nothing. Can anybody give some suggestion?
By the way, where can I find examples indicating how to use the large amount of procfs files!!
Thanks a lot!

Answer 1

What is the best source to access /proc file system code snippet. I am interested in calculating %cpu utilization of a running process, just like ps command.
Any pointer/help is appreciated.
thanks