ELEMENT_TIMEOUT
tsleep(&rl_test, 0, "rl_test", ELEMENT_TIMEOUT * hz / 2);
tsleep(&rl_test, 0, "rl_test", ELEMENT_TIMEOUT * hz * 2);
callout_reset(&rl->rl_gc, ELEMENT_TIMEOUT * hz,
expiry.tv_sec -= ELEMENT_TIMEOUT;