#!/usr/bin/perl

# alphaload - authored by pal@ekran.no, Thu Jun 26 10:05:47 CEST 2014
# -------------------------------------------------------------------

# runs calculations (simple math) on X cores for Y seconds
# example: ./alphaload.pl 4 10 
# which would run on 4 cores for 10 seconds
#
## note: program does not care if you overtax the CPU (run on more than available cores)
#

my $cores=$ARGV[0] || die ("usage: alphaload <cores> <seconds>\n");
my $runs=$ARGV[1] || die ("usage: alphaload <cores> <seconds>\n");
my @pids;

for ($ccnt=0; $ccnt<$cores; $ccnt++)
{
	$pid=fork();
	if ($pid)
	{
		($itter,$secs)=it($runs);
		($mitter)=sprintf ("%2.2f",(($itter/1000)/1000));

		($itsec)=($itter/$secs);
		($mitsec)=(($itsec/1000)/1000);
		$itsec=int($itsec);
		$mitsec=sprintf ("%2.2f",$mitsec);

		print "Thread ".$ccnt." ran for ".$secs." seconds doing ".$itter." (".$mitter."M) iterations, which is ".$itsec." (".$mitsec."M) I/sec.\n";
		exit();
	}
}
sleep ($runs+2); # this works as long as you don't spawn more than you have cores available

sub it()
{
	my ($lruns)=@_;

	my $t1=time();
	my $s=0;

	$cnt=0; $x=0;
	while ($s < $lruns)
	{
		$cnt++;
		# do some CPU calculation
		$x=sqrt($cnt*3.14159);
		$t2=time();
		$s=$t2-$t1;
	}
	return ($cnt,$s);
}