On 12/22/06, Gerrit Renker <gerrit@xxxxxxxxxxxxxx> wrote:
[CCID 3]: Fix packet tardiness BUG Problem: -------- Due to packet scheduling in CCID 3, it can happen that the actual send time of a packet is later than t_now: in this case t_nom < t_now. This case brings the entire packet scheduling out of sync, since the next packet is scheduled at t_nom + t_ipi, and t_nom is in the past. Fix: ---- Update t_nom to t_now whenever a packet is late due to scheduling (and then t_nom < t_now). This update takes place in ccid3_hc_tx_ send_packet. In between calls to this function, it is irrelevant if t_nom < t_now (since it will be caught eventually).
Agree with the problem statement and your fix helps but I think this fix isn't quite right and mine uses a bit too much CPU resource. The problem with yours is that it resets t_nom whenever it is late rather than just due to t_ipi changing. The problem like this is that if the packet is late for other reasons then we shouldn't slow down following packets as it hurts performance. Many cases the result will be negative but low value. I'll go back and rework my patch a little. Ian -- Web: http://wand.net.nz/~iam4 Blog: http://imcdnzl.blogspot.com WAND Network Research Group - To unsubscribe from this list: send the line "unsubscribe dccp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
