#!/usr/bin/perl

use Fcntl;
my $fifo = "/tmp/fixfreq";

system "mkfifo", $fifo;
chmod 0600, $fifo;

sysopen( READ_PIDS, $fifo, O_NONBLOCK|O_RDONLY) or die "Can't open modem: $!\n";


END {
	set( 0 );
	close READ_PIDS;
	unlink $fifo;
}

sub bye { exit; }

$SIG{TERM} = \&bye;
$SIG{INT} = \&bye;

my $now_is = "";
sub set
{
	my $num = shift;
	my $set_to = $num ? "performance" : "ondemand";
	return if $now_is eq $set_to;
	$now_is = $set_to;
	foreach my $gov ( glob "/sys/devices/system/cpu/cpu[0-9]*/cpufreq/scaling_governor" ) {
		open GOV, ">", $gov;
		print GOV $set_to;
		close GOV;
	}
}

my %pids;

while ( 1 ) {
	foreach my $pid ( keys %pids ) {
		unless ( -d "/proc/".$pid ) {
			delete $pids{ $pid };
		}
	}
	while ( my $pid = <READ_PIDS> ) {
		chomp $pid;
		if ( -d "/proc/$pid" ) {
			$pids{ $pid } = 1;
		}
	}
	set( keys %pids );
	sleep 1;
}