Hi, We are working on a new TCP congestion control algorithm, aiming at satisfying new requirements coming from current networks. For instance, adaptation to bandwidth/delay changes (due to mobility, dynamic switching, handover), and optimal exploitation of very high link capacity and efficient transmission of small objects, irrespective of the underlying link characteristics.
TCP Wave (TCPW) replaces the window-based transmission paradigm of the standard TCP with a burst-based transmission, the ACK-clock scheduling with a self-managed timer and the RTT-based congestion control loop with an Ack-based Capacity and Congestion Estimation (ACCE) module. In non-technical words, it sends data down the stack when its internal timer expires, and the timing of the received ACKs contribute to updating this timer regularly. We tried to add this new sender paradigm without deeply touching existing code. In fact, we added four (optional) new congestion control functions: + /* get the expiration time for the send timer (optional) */ + unsigned long (*get_send_timer_exp_time)(struct sock *sk); + /* no data to transmit at the timer expiration (optional) */ + void (*no_data_to_transmit)(struct sock *sk); + /* the send timer is expired (optional) */ + void (*send_timer_expired)(struct sock *sk); + /* the TCP has sent some segments (optional) */ + void (*segment_sent)(struct sock *sk, u32 sent); And a timer (tp->send_timer) which uses a send callback to push data down the stack. If the first of these function, get_send_timer_exp_time, is not implemented by the current congestion control, then the timer sending timer is never set, therefore falling back to the old, ACK-clocked, behavior. The TCPW module itself extensively make use of the existing infrastructure and parameters to calculate its timer, plus some heuristics when it is not possible to have trustworthy values from the network. You can find more stuff related to TCPW (extended results, the test programs used and the setup for the experiments, a document describing the algorithm in detail and so on) at: [1] http://tlcsat.uniroma2.it/tcpwave4linux/ We would greatly appreciate any feedback from you, comments, suggestions, corrections and so on. Thank you for your attention. Cesare, Francesco, Ahmed, Natale Natale Patriciello (5): tcp: Added callback for timed sender operations tcp: Implemented the timing-based operations tcp: PSH frames sent without timer involved tcp: Add initial delay to allow data queueing wave: Added basic version of TCP Wave MAINTAINERS | 6 + include/linux/tcp.h | 3 + include/net/tcp.h | 8 + net/ipv4/Kconfig | 16 + net/ipv4/Makefile | 1 + net/ipv4/tcp.c | 8 +- net/ipv4/tcp_ipv4.c | 2 + net/ipv4/tcp_output.c | 73 +++- net/ipv4/tcp_wave.c | 914 ++++++++++++++++++++++++++++++++++++++++++++++++++ 9 files changed, 1023 insertions(+), 8 deletions(-) create mode 100644 net/ipv4/tcp_wave.c -- 2.13.2
