iodev_cmp
int c = iodev_cmp((struct iodev_snapshot *)is1,
if (iodev_cmp(tmp, iodev) > 0) {
int iodev_cmp(struct iodev_snapshot *io1, struct iodev_snapshot *io2);
if (iodev_cmp(d1, d2) < 0) {
} else if (iodev_cmp(d1, d2) > 0) {