SCTP supports multistreaming. This feature solves the head-of-line blocking problem of TCP and makes SCTP a proper transport for signaling. However, the multistreaming feature of SCTP can be further exploited to provide QoS scheduling among streams. This is what we want to add in this patch. In the current implementation, multiple streams in an SCTP association is scheduled in a first-come-first-serve (FCFS) fashion. We would like to augment this simple algorithm with many other scheduling algorithms and let the application choose which scheduling they want to use. We provide a general interface in the kernel so that different scheduling algorithms can be implemented as kernel modules. We also extend the SCTP socket API to include a new socket option for applications to choose and configure the scheduling they want. This approach is inspired by the pluggable TCP congestion control mechanism in the Linux kernel. An application of this feature is as follow: suppose two users are chatting with each other over an SCTP-based instant messenger. Meantime, they are exchanging photos. So there are two streams in this scenario: one for instant messages and the other for photo transfer. In the current implementation, the user cannot specify the scheduling of the two streams so that the instant messages may be delayed by the bulk data transfer when the available bandwidth is limited. With our extension, the user could choose priority queue scheduling among the streams and put instant messages on the higher priority queue. Thus, we can prevent the previous problems and decrease the latency experienced by the instant messages. There may be many other possible applications of this patch since it provides a general framework to implement many possible scheduling algorithms. All following patches should be applied to kernel 2.6.32.8 sequentially. -- ======================== Yaogong Wang, PhD candidate Department of Computer Science North Carolina State University http://www4.ncsu.edu/~ywang15/ ======================== -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
