SEQ_DIFF
offset = BM_STR_OFF(SEQ_DIFF(iter->snx, iter->bsn));
if (unlikely(SEQ_DIFF(tid_info->snx, tid_info->bsn) >=
off = SEQ_DIFF(seq, agg->bsn);
off = SEQ_DIFF(seq, tid_info->bsn);
off = SEQ_DIFF(tid_info->snx, tid_info->bsn);