$d->{swap} = read_cgroup_value('memory', $vmid, 'memory.memsw.usage_in_bytes') - $mem_usage_in_bytes;
my $blkio_bytes = read_cgroup_value('blkio', $vmid, 'blkio.throttle.io_service_bytes', 1);
$d->{swap} = read_cgroup_value('memory', $vmid, 'memory.memsw.usage_in_bytes') - $mem_usage_in_bytes;
my $blkio_bytes = read_cgroup_value('blkio', $vmid, 'blkio.throttle.io_service_bytes', 1);