david@ukma.UUCP (David Herron, NPR Lover) (10/20/85)
I wrote this program after a couple of days in a row of news
arriving and being unbatched during the day. News unbatching
doesn't mix well with troffing and macsyma. Our poor 750 was
at load averages hardly ever seen before (~20!).
This is a modified form of our play program. It sits above
the program and monitors the load average. If the load average
gets high it nices the process group. If the load average comes
back down the nice goes down also. After a couple of days of use
this looks like a useful program.
Sigh! I know.... post it to net.sources.4bsd. Well, there aint
one, so there! (phthththth) (We need a little icon for raspberries)
: This is a shell archive, meaning:
: 1. Remove everything above the '#! /bin/sh' line.
: 2. Save the resulting text in a file.
: 3. Execute the file with /bin/sh '(not csh)' to create the files:
: 'limit.1'
: 'limit.c'
: 'Makefile'
: This archive created: 'Fri Oct 18 22:09:59 1985
'
: By: 'David Herron, NPR Lover ()'
export PATH; PATH=/bin:$PATH
echo shar: extracting "'limit.1'" '(1501 characters)'
if test -f 'limit.1'
then
echo shar: will not over-write existing file "'limit.1'"
else
sed 's/^X//' >'limit.1' <<'SHAR_EOF'
X.TH LIMIT 1L "University of Kentucky" "4.2BSD"
X.SH NAME
Xlimit \- limit processor usage of a program by renicing
X.SH USAGE
Xlimit
X.I file
X[
X.I args
X]
X.SH DESCRIPTION
X.LP
XLimit(1) is meant to limit processor usage by background processes.
XIt fork()'s and exec()'s
X.I file
Xwith
X.I args
X(if any) then goes into an infinite loop watching the load average.
XIf the load average becomes very high then it changes the
X.I nice
Xvalue for the process group to successively higher numbers.
XIf the load average drops back down it again lowers the nice value.
XIf the load average is nonexistant it sets the nice value
Xa little bit below 0.
X.LP
XIntended usage of the program is via a shell script, for instance
Xreplace /usr/bin/rnews with:
X.RS
X.nf
X.ft L
X
X#! /bin/sh
Xexec /usr/local/limit /usr/lib/news/rnews
X
X.ft P
X.RE
X.LP
XWhich will limit the impact of rnews upon your system.
X.SH AUTHOR
XDavid Herron
X.br
XUniversity of Kentucky, Computer Science
X.br
Xcbosgd!ukma!david, david@ukma.bitnet
X.SH BUGS
XThis program is a little simple minded.
XThere are some cases where you will want all but one of a set of
Xprocess groups to be niced down, and the other given extra priority.
X.LP
XNote that this program needs to be setuid to root, so it can
Xraise and lower process priorities at will.
XHowever, the child process sets its uid and gid back to the real ones
Xbefore doing the exec().
X.LP
XAs written it is 4.2BSD specific.
XHowever if System V provided functions similar to load average and renice
Xthen it could run there.
SHAR_EOF
if test 1501 -ne "`wc -c < 'limit.1'`"
then
echo shar: error transmitting "'limit.1'" '(should have been 1501 characters)'
fi
fi # end of overwriting check
echo shar: extracting "'limit.c'" '(2521 characters)'
if test -f 'limit.c'
then
echo shar: will not over-write existing file "'limit.c'"
else
sed 's/^X//' >'limit.c' <<'SHAR_EOF'
X/*
X * USAGE -- limit file args
X *
X * SYNOPSIS
X *
X * file is a file to exec
X * args are the arguments for the exec'd program
X *
X * Limit constantly watches the load average and if the load average
X * gets very high will renice its process group to higher values.
X *
X * Note that this program is dependent on such Bezerkeley ideas
X * as "load average", and "renice".
X *
X * AUTHOR
X * David Herron
X * University of Kentucky, Computer Science
X */
X
X
X#include <stdio.h>
X#include <nlist.h>
X#include <signal.h>
X#include <sys/time.h>
X#include <sys/resource.h>
X
Xstruct nlist avenrun[] = {
X { "_avenrun" },
X { (char *)0 }
X};
X
Xextern char **environ;
X
Xint pid; /* Process id of child being monitored */
Xint lastpr;
X
X
X#define NAMELIST "/vmunix"
X#define CHECK_TIME 10 /* Time between load average checks in seconds */
X
X#define MUCHTOOHIGH 6.0
X#define TOOHIGH 5.0
X#define HIGH 4.0
X#define MODERATE 3.0
X#define LIGHT 2.0
X#define NONEXISTANT 1.0
X#define NOLOAD 0.0
X
X
Xmain(argc,argv)
Xint argc;
Xchar *argv[];
X{
X void check();
X void leave();
X void set();
X extern char *rindex();
X double avg[3];
X char buf[256];
X char *s;
X
X if (argc < 2) {
X fprintf(stderr, "Usage: limit file [args]\n");
X exit(1);
X }
X loadav(avg);
X lastpr = 200;
X if((pid=fork()) == 0) {
X strcpy(buf, argv[1]);
X s = rindex(argv[1], '/');
X argv[1] = ++s;
X setuid(getuid());
X setgid(getgid());
X execve(buf, &argv[1], environ);
X sprintf(buf, "Unknown program: %s\n", argv[1]);
X perror(buf);
X exit(1);
X }
X setuid(0);
X setgid(0);
X signal(SIGCHLD, leave);
X signal(SIGINT, SIG_IGN);
X signal(SIGQUIT, SIG_IGN);
X check();
X wait(0);
X}
X
Xvoid leave() { exit(0); }
X
Xvoid check()
X{
X double avg[3];
X double t;
X
X signal(SIGALRM, check);
X loadav(avg);
X t = avg[1];
X if (t > MUCHTOOHIGH)
X set(17);
X else if(t > TOOHIGH)
X set(15);
X else if(t > HIGH)
X set(13);
X else if(t > MODERATE)
X set(10);
X else if(t > LIGHT)
X set(5);
X else if (t > NONEXISTANT)
X set(0);
X else
X set(-2);
X alarm(CHECK_TIME);
X}
X
Xvoid set(prio)
Xint prio;
X{
X static int pgrp = 0;
X
X if (prio == lastpr)
X return;
X if (!pgrp)
X pgrp = getpgrp(pid);
X setpriority(PRIO_PGRP, pgrp, prio);
X /* setpriority(PRIO_PROCESS, pid, prio); */
X lastpr = prio;
X}
X
Xloadav(avg)
Xregister double *avg;
X{
X register int kmem;
X
X if ((kmem = open("/dev/kmem", 0)) < 0)
X goto bad;
X nlist(NAMELIST, avenrun);
X if (avenrun[0].n_type == 0) {
X close(kmem);
Xbad:
X avg[0] = 0.0;
X avg[1] = 0.0;
X avg[2] = 0.0;
X return;
X }
X
X lseek(kmem, (long) avenrun[0].n_value, 0);
X read(kmem, (char *)avg, 3*sizeof(double));
X close(kmem);
X}
SHAR_EOF
if test 2521 -ne "`wc -c < 'limit.c'`"
then
echo shar: error transmitting "'limit.c'" '(should have been 2521 characters)'
fi
fi # end of overwriting check
echo shar: extracting "'Makefile'" '(188 characters)'
if test -f 'Makefile'
then
echo shar: will not over-write existing file "'Makefile'"
else
sed 's/^X//' >'Makefile' <<'SHAR_EOF'
X# Makefile for limit
X
Xall: limit install
X
Xlimit: limit.o
X cc limit.o -o limit
X
Xinstall:
X install -m 6755 -c -s limit /usr/local/limit
X
Xshar:
X shar -a limit.1 limit.c Makefile >limit.shar
SHAR_EOF
if test 188 -ne "`wc -c < 'Makefile'`"
then
echo shar: error transmitting "'Makefile'" '(should have been 188 characters)'
fi
fi # end of overwriting check
: End of shell archive
exit 0
--
David Herron, cbosgd!ukma!david, david@UKMA.BITNET.
English is a second language to me -- Baby talk was my first language.