+ len += q->packet_overhead;
+
+ if (q->cell_size) {
+ u32 cells = reciprocal_divide(len, q->cell_size_reciprocal);
+
+ if (len > cells * q->cell_size) /* extra cell needed for remainder */
+ cells++;
+ len = cells * (q->cell_size + q->cell_overhead);
+ }
+
+ ticks = (u64)len * NSEC_PER_SEC;
+
+ do_div(ticks, q->rate);