round_clstr
imagesz = round_clstr(imgsz * secsz);
clstr_l2tbls = round_clstr(clstr_imgsz * 8) >> clstr_log2sz;
clstr_l1tblsz = round_clstr(clstr_l2tbls * 8) >> clstr_log2sz;
clstr_rcblks = round_clstr((nclstrs + n) * 2) >> clstr_log2sz;
clstr_rctblsz = round_clstr(clstr_rcblks * 8) >> clstr_log2sz;
refcnt_clstrs = round_clstr(clstr_rcblks * 8) >> clstr_log2sz;
clstr_rcblks = round_clstr((nclstrs + n) * 2) >> clstr_log2sz;