You can start with Sys::CpuLoad, it works under Linux and BSD; then you can glue it to Proc::ProcessTable.

Ciao, Valerio

Update: i wrote this little test:

#!/usr/bin/perl

use strict;
use Sys::CpuLoad;
use Proc::ProcessTable;

use vars qw( $sleep_time @memory $memory_size $count $threshold $progr
+am @pids );

$program = '/usr/bin/perl';
$threshold = 1; #load
$sleep_time = 1; #seconds
$memory_size = 10;
$count = 0;

while (1) {
  if (load_average() > $threshold) {
    @pids = search_procs();
    if (@pids) {
      killall(@pids);
    }
  }

  $count++;
  sleep $sleep_time;
}

exit;

sub load_average {
  my ($last, $average);

  $last = (Sys::CpuLoad::load())[0];
  $memory[$count % $memory_size] = $last;
  $average += $_ foreach @memory;
  $average = $average / $memory_size;
  return $average;
}

sub search_procs {
  my ($ppt, $proc, @pids);
  $ppt = new Proc::ProcessTable;
  foreach $proc (@{$ppt->table}) {
    next unless ($proc->{exec} eq $program);
    push @pids, $proc->{pid};
  }
  return @pids;
}

sub killall
{
  print join(' ', @_), "\n";
}
[download]

This code is only a proof of concept.

--
perl: code of the samurai

--t. alex
but my friends call me T.