lars@myab.se (Lars Pensj|) (05/25/89)
A program (background deamon) that computes the load average on a
SYSV.3 machine. Probably easy to port to SYSV.2.
#--------CUT---------CUT---------CUT---------CUT--------#
#########################################################
# #
# This is a shell archive file. To extract files: #
# #
# 1) Make a directory for the files. #
# 2) Write a file, such as "file.shar", containing #
# this archive file into the directory. #
# 3) Type "sh file.shar". Do not use csh. #
# #
#########################################################
#
#
echo Extracting lload.c:
sed 's/^Z//' >lload.c <<\STUNKYFLUFF
Z/*
Z * Load Average deamon.
Z *
Z * The load average is updated every constant time interval, and the result
Z * written to a file as 3 double values.
Z *
Z * The load average is for the last 1, 5 and 15 minutes (3 values).
Z *
Z * A second argument (-v) will set the program in a verbose mode, writing
Z * the load average to the standard output and not to the file.
Z *
Z * Preferably start this process from the inittab. It needs special
Z * priviledges to read from /dev/kmem.
Z *
Z * The following processes are regarded as "runnning":
Z * A process that has the SRUN status (simply running).
Z * A process that is being created (SIDLE).
Z * A process that is being swapped out (SXBRK).
Z * A process that waits for disk I/O.
Z *
Z * A process is regarded as waiting for disk I/O if it is SSLEEP and
Z * has wchan set to a buf in the buffer pool.
Z *
Z * The sleep is implemented using poll on a stream device, not the
Z * more usual sleep() call. Why ?
Z * Because you do not want to wake up simultaneosly with other programs
Z * doing sleep(), which might give wrong load average.
Z * Of course, if you do not have the stream pipe device, use the normal
Z * sleep().
Z */
Z
Z#include <fcntl.h>
Z#include <nlist.h>
Z#include <stdio.h>
Z#include <stropts.h>
Z#include <poll.h>
Z#include <math.h>
Z#include <sys/types.h>
Z#include <sys/param.h>
Z#include <sys/buf.h>
Z#include <sys/immu.h>
Z#include <sys/region.h>
Z#include <sys/var.h>
Z#include <sys/proc.h>
Z
Z/* #define DEBUG */ /* Will append all values in a debug file */
Z
Z#define LOADAV "/etc/loadav" /* Where to write the load avarge */
Z#define STREAM_PIPE "/dev/spx" /* Used for polling with timeout */
Z
Z/*
Z * You may or may not need the '_' in the following names.
Z */
Z
Z#define VAR_NAME "_v"
Z#define BUF_NAME "_buf"
Z#define PROC_NAME "_proc"
Z
Zstruct nlist nl[] = {
Z {VAR_NAME},
Z {BUF_NAME},
Z {PROC_NAME},
Z {0},
Z};
Z
Zint loadfile; /* file descr to result file */
Zstruct proc *p;
Zstruct var v;
Zint kmem;
Zstruct nlist *v_p, *proc_p, *buf_p;
Zint size;
Zint first_buf, last_buf;
Zint sleeping = 1; /* Poll frequency in seconds */
Zint verbose = 0;
Z
Zdouble av[3] = { 0.0, 0.0, 0.0 }; /* The loadaverage */
Zdouble apa[3]; /* Holding constants */
Z
Zmain(argc, argv)
Z char **argv;
Z{
Z int i, n, n_run, n_disk;
Z#ifdef DEBUG
Z int debug_fd;
Z char buff[100];
Z debug_fd = open("/tmp/loadavdebug", O_CREAT|O_WRONLY);
Z#endif
Z
Z if (argc == 2 && strcmp(argv[1], "-v") == 0) {
Z verbose = 1;
Z printf("Verbose\n");
Z }
Z kmem = open("/dev/kmem", 0);
Z if (kmem == -1) {
Z perror("/dev/kmem");
Z exit(1);
Z }
Z if (!verbose) {
Z loadfile = open(LOADAV, 1|O_CREAT,0664);
Z if (loadfile == -1) {
Z fprintf(stderr, "%s:", argv[0]);
Z perror(LOADAV);
Z exit(1);
Z }
Z }
Z if (nlist("/unix", nl) == -1) {
Z perror("nlist");
Z exit(1);
Z }
Z for (i=0; nl[i].n_name; i++) {
Z if (nl[i].n_value == 0) {
Z fprintf(stderr, "Could not get address for %s\n", nl[i].n_name);
Z exit(1);
Z }
Z if (strcmp(nl[i].n_name, VAR_NAME) == 0)
Z v_p = &nl[i];
Z if (strcmp(nl[i].n_name, PROC_NAME) == 0)
Z proc_p = &nl[i];
Z if (strcmp(nl[i].n_name, BUF_NAME) == 0)
Z buf_p = &nl[i];
Z }
Z /*
Z * Setup the constants used for computing load average.
Z */
Z apa[0] = exp(-sleeping/60.0);
Z apa[1] = exp(-sleeping/300.0);
Z apa[2] = exp(-sleeping/900.0);
Z /*
Z * Start looping
Z */
Z while(1) {
Z /*
Z * Read the 'v' structure every time. It says how
Z * many procs are used.
Z */
Z if (lseek(kmem, v_p->n_value, 0) == -1) {
Z perror("lseek v");
Z exit(1);
Z }
Z if (read(kmem, &v, sizeof v) == -1) {
Z perror("read v");
Z exit(1);
Z }
Z size = (struct proc *)v.ve_proc - (struct proc *)proc_p->n_value;
Z first_buf = buf_p->n_value;
Z last_buf = first_buf + v.v_buf * sizeof (struct buf);
Z if (lseek(kmem, proc_p->n_value, 0) == -1) {
Z perror("lseek proc");
Z exit(1);
Z }
Z p = (struct proc *)malloc(size * sizeof (struct proc));
Z if (p == 0) {
Z fprintf(stderr, "Could not malloc %d bytes\n",
Z size * sizeof (struct proc));
Z exit(1);
Z }
Z n = read(kmem, p, size * sizeof (struct proc));
Z if (n != size * sizeof (struct proc)) {
Z if (n == -1) {
Z perror("read procs");
Z exit(1);
Z }
Z fprintf(stderr, "Could only read %d (%d) procs\n",
Z n, size);
Z size = n / sizeof (struct proc);
Z }
Z n_run = 0;
Z n_disk = 0;
Z for (i=0; i<size; i++) {
Z if (p[i].p_stat == SRUN || p[i].p_stat == SIDL ||
Z p[i].p_stat == SXBRK)
Z n_run++;
Z else if (p[i].p_stat == SSLEEP &&
Z (unsigned int)p[i].p_wchan >= first_buf &&
Z (unsigned int)p[i].p_wchan < last_buf)
Z n_disk++;
Z }
Z /*
Z * Update the load average using a decay filter.
Z */
Z for (i = 0; i < 3; i++)
Z av[i] = apa[i] * av[i] + (n_run + n_disk) * (1.0 - apa[i]);
Z if (!verbose) {
Z if (lseek(loadfile, 0L, 0) == -1) {
Z fprintf(stderr, "Couldn't seek in %s\n", LOADAV);
Z exit(1);
Z }
Z if (write(loadfile, (char *)av, sizeof av) != sizeof av) {
Z perror(argv[0]);
Z exit(1);
Z }
Z } else
Z printf("(%d %d) %f %f %f\n", n_run, n_disk,
Z av[0], av[1], av[2]);
Z#ifdef DEBUG
Z sprintf(buff, "(%d %d) %4.2f\n", n_run, n_disk,
Z av[0]);
Z write(debug_fd, buff, strlen(buff));
Z#endif
Z nap(sleeping * 1000);
Z free(p);
Z }
Z}
Z
Z/*
Z * Use a stream pipe to implement a sleep.
Z * We have a stream pipe for ourselves, so we know noone will write
Z * on it.
Z */
Znap(milli) {
Z static int fd = 0;
Z static struct pollfd pollfd;
Z
Z if (fd == 0) {
Z fd = open(STREAM_PIPE, 0);
Z if (fd == -1) {
Z perror(STREAM_PIPE);
Z exit(1);
Z }
Z pollfd.fd = fd;
Z pollfd.events = POLLIN;
Z }
Z if (poll(&pollfd, 1, milli) == -1) {
Z perror("nap: poll");
Z exit(1);
Z }
Z if (pollfd.revents != 0) {
Z fprintf(stderr, "nap: poll: got something\n");
Z exit(1);
Z }
Z}
STUNKYFLUFF
set `wc lload.c`
if test 231 != $1
then
echo lload.c: Checksum error. Is: $1, should be: 231.
fi
echo All done
exit 0
--
Lars Pensj|
lars@myab.se