Virtual Memory in SunOs

puts(buffer
should be
puts(buffer);

Thank you very much for your answer, rbr, however, I need to get those information from the kernel. As I've mentioned in the question, I need to know which header file or library file to call or include, eg. kstat.h, vmsystm.h etc. by the way, I tried running your code in SunOs, it was giving me an error: "Segmentation Fault".
Thanks for helping.
Regards.

SkyWalker,

what version of SunOS (show me the output of 'uname -a')?

Tobias

Hi thoellri, here's the output
   SunOS deneb 5.5.1 Generic sun4c sparc SUNW,Sun_4_60
Please allow me to repeat that the program must get virtual memory information from the kernel directly, no cheats. The reason for me saying this is because there have been several friends who suggested other ways to do it.
Thank you very very much for your help.
Regards.

Hope this helps
  Tobias

/*
   Compile with: gcc -o kstat kstat.c -lkstat
   Execute as:   kstat
   Will display the free memory, reserved swap, avail swap and free swap every second. Read sys/sysinfo.h and kstat.h include files.
*/

#include <stdio.h>
#include <kstat.h>
#include <sys/sysinfo.h>

#define BYTES_PER_PAGE 8192
#define KBYTE          1024
#define MUL            (BYTES_PER_PAGE/KBYTE)

void main(int argc, char*argv[])
{
  kstat_ctl_t    *kc;
  kstat_t        *ksp;
  int            first=1;
  vminfo_t       last,vm;

  kc  = kstat_open();
  while(1) {
    ksp = kstat_lookup(kc, "unix", 0, "vminfo");
    if (ksp) {
      kstat_read(kc, ksp, &vm);
      if (first) {
      first=0;
      } else {
      printf("---------------------------------\n");
      printf("freemem       =%8llu KByte\n",(vm.freemem-last.freemem)*MUL);
      printf("reserved swap =%8llu KByte\n",(vm.swap_resv-last.swap_resv)*MUL);
      printf("allocated swap=%8llu KByte\n",(vm.swap_alloc-last.swap_alloc)*MUL);
      printf("avail swap    =%8llu KByte\n",(vm.swap_avail-last.swap_avail)*MUL);
      printf("free swap     =%8llu KByte\n",(vm.swap_free-last.swap_free)*MUL);
      }
      last=vm;
    }
    sleep(1);
    kstat_chain_update(kc);
  }
  kstat_close(kc);
  exit(0);
}

Thank you very very much, thoellri. The program works fine. However, I would like to ask several questions.

1. why are we defining BYTES_PER_PAGES, KBYTE and MUL?
2. how do I use other structs in sysinfo.h, eg. cpu_vminfo?

Please don't give your answers as comments because I can't reward you in this way. I have slightly increased the points, just to show my appreciation.

Once again thank you very very much and regards.

Dear thoellri, sorry to trouble you again, I've tried your little function and here are the warning message I've got
kstat.c:42: warning: type mismatch with previous external decl
kstat.c:17: warning: previous external decl of `print_chain'
kstat.c:42: warning: type mismatch with previous implicit declaration
kstat.c:17: warning: previous implicit declaration of `print_chain'
kstat.c:42: warning: `print_chain' was previously implicitly declared to return
`int'
but the program runs just fine. However, I do have something that I don't understand

"Now you have to replace the kstat_lookup() call to search for "cpu_stat",  0, "cpu_stat0" and if you get a valid ksp, then do the kstat_read, but this passing a pointer to a    cpu_stat_t structure, which will be filled in for you."

I don't quite understand the above paragraph. Would you please explain in greater detail, hopefully through an example, if you don't mind :p
yet, another question, can you tell me a little about LD_LIBRARY_PATH.
I have increased the points again just to show my appreciation.
Thank you very much and regards.

SkyWalker,

here is the complete code again. I guess you forgot to copy the "void" in front of print_chain, because I don't get the warning here.
Anyway, I added the cpu_stat thingie which you can see in the code below. As we accessed the vminfo-structure I also access the cpu_stat structure which contains a hell of a lot of information. The kstat_lookup("cpu_stat"...) line asks the kstat-library to locate the address of the kernel-structure we are looking for. If kstat_lookup returns a valid pointer, then you can read the structure using this pointer and the kstat_read() function. kstat_read simply fills in the cpu_stat_t structure in this case and I can examine the struct after it has been read. I do the same as with vminfo and make a copy of the structure, because we are interested in the deltas and not the absolute values. The number printer for "stat:syscall" is the number of syscalls which have been executed in the last second. Is this enough for an explanation?

LD_LIBRARY_PATH: Is used in two contexts. First the linking context, where LD_LIBRARY_PATH is defined during an ld-operation. It then defines a list of directories in which to search for  libraries specified with the -l option.  Multiple directories are separated by a colon.  In the  most  general  case,  it will  contain  two directory lists separated by a semi-colon:
                 dirlist1;dirlist2
If ld is called with any number of occurrences  of  -L, as in:
                 ld ... -Lpath1 ... -Lpathn ...
then the search path ordering is:
                 dirlist1 path1 ... pathn dirlist2 LIBPATH

When the list of directories does not contain  a  semicolon, it is interpreted as dirlist2.

The second (and more important context) where LD_LIBRARY_PATH is used, is to specify library  search directories   to  the  runtime  linker.   That  is,  if LD_LIBRARY_PATH exists in the environment, the  runtime linker  will search the directories named in it, before its default directory, for shared objects to be  linked with the program at execution.

Note:  When running a set-user-ID or set-group-ID  program, the runtime linker will only search for libraries in any full pathname specified within the executable as a   result  of  a  runpath  being  specified  when  the executable  was  constructed,  or  in  /usr/lib.    Any library  dependencies  specified  as relative pathnames will be silently ignored.

Example: The "usual" LD_LIBRARY_PATH for SunOS5.5.1 systems looks like this one:
      LD_LIBRARY_PATH=/usr/lib:/usr/openwin/lib

Now, I happen to have built some shared libraries which are needed to execute certain programs. These shared libraries are installed in /usr/local/lib. Without special arguments ot the link-editor (ld) and without adjusting my LD_LIBRARY_PATH the system will tell me that a certain library (.so file) cannot be found when I try to execute a program which relies on a shared library in /usr/local/lib. The solution:
      LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib

I have this line in my shell-startup file and it will add the "/usr/local/lib" directory to the runtime linkers search path.

Another solution involves the -R option for the link-editor, which allows you to embed certain search-paths into an executable. Have a look at the ld-manpage.

To see the runtime-linker in action and to get a feel for it, try the following secrets :-)

I assume you use bourne shell ? Or ksh ? and not the evil csh :-( Enter the following:

     LD_DEBUG=files ls

Enter it eactly as written, there is a space between "files" and "ls". This tells the runtime linker to spit out some information about the files it processes. And another one which will probably blow you away:

     LD_DEBUG=bindings ls

You'll see exactly what shared libraries get pulled in for what symbols - neat?

Hope this is enough
    Tobias




#include <stdio.h>
#include <kstat.h>
#include <sys/sysinfo.h>

#define BYTES_PER_PAGE 8192
#define KBYTE          1024
#define MUL            (BYTES_PER_PAGE/KBYTE)

void print_chain(kstat_ctl_t *kc)
{
  kstat_t *ksp;
  for (ksp = kc->kc_chain; ksp != NULL; ksp = ksp->ks_next) {
    printf("Module: %s Class: %s Name: %s\n", ksp->ks_module, ksp->ks_class, ksp->ks_name);
  }
}

void main(int argc, char*argv[])
{
  kstat_ctl_t    *kc;
  kstat_t        *ksp;
  int            first=1;
  vminfo_t       vmlast,vm;
  cpu_stat_t     statlast, cpu_stat;

  kc  = kstat_open();
  print_chain(kc);
  while(1) {
    ksp = kstat_lookup(kc, "unix", 0, "vminfo");
    if (ksp) {
      kstat_read(kc, ksp, &vm);
      if (!first) {
        printf("---------------------------------\n");
        printf("freemem       =%8llu KByte\n",(vm.freemem-vmlast.freemem)*MUL);
        printf("reserved swap =%8llu KByte\n",(vm.swap_resv-vmlast.swap_resv)*MUL);
        printf("allocated swap=%8llu KByte\n",(vm.swap_alloc-vmlast.swap_alloc)*MUL);
        printf("avail swap    =%8llu KByte\n",(vm.swap_avail-vmlast.swap_avail)*MUL);
        printf("free swap     =%8llu KByte\n",(vm.swap_free-vmlast.swap_free)*MUL);
      }
      vmlast=vm;
    }
    ksp = kstat_lookup(kc, "cpu_stat", 0, "cpu_stat0");
    if (ksp) {
      kstat_read(kc, ksp, &cpu_stat);
      if (!first) {
        printf("stat:syscall  =%8lu\n",
           cpu_stat.cpu_sysinfo.syscall-statlast.cpu_sysinfo.syscall);
      }
      statlast=cpu_stat;
    }
    first=0;
    sleep(1);
    kstat_chain_update(kc);
  }
  kstat_close(kc);
  exit(0);
}