LVL_DEPTH
#define WHEEL_TIMEOUT_CUTOFF (LVL_START(LVL_DEPTH))
#define WHEEL_TIMEOUT_MAX (WHEEL_TIMEOUT_CUTOFF - LVL_GRAN(LVL_DEPTH - 1))
for (i = 0; i < LVL_DEPTH; i++) {
for (lvl = 0; lvl < LVL_DEPTH; lvl++, offset += LVL_SIZE) {
#define WHEEL_SIZE (LVL_SIZE * LVL_DEPTH)
struct hlist_head heads[LVL_DEPTH];
} else if (LVL_DEPTH > 8 && delta < LVL_START(8)) {
idx = calc_index(expires, LVL_DEPTH - 1, bucket_expiry);