From 4821a076eb602a6238528e9ebafeac853c833415 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Tue, 7 Mar 2023 16:23:26 -0500 Subject: sctp: add fair capacity stream scheduler As it says in rfc8260#section-3.5 about the fair capacity scheduler: A fair capacity distribution between the streams is used. This scheduler considers the lengths of the messages of each stream and schedules them in a specific way to maintain an equal capacity for all streams. The details are implementation dependent. interleaving user messages allows for a better realization of the fair capacity usage. This patch adds Fair Capacity Scheduler based on the foundations added by commit 5bbbbe32a431 ("sctp: introduce stream scheduler foundations"): A fc_list and a fc_length are added into struct sctp_stream_out_ext and a fc_list is added into struct sctp_stream. In .enqueue, when there are chunks enqueued into a stream, this stream will be linked into stream-> fc_list by its fc_list ordered by its fc_length. In .dequeue, it always picks up the 1st skb from stream->fc_list. In .dequeue_done, fc_length is increased by chunk's len and update its location in stream->fc_list according to the its new fc_length. Note that when the new fc_length overflows in .dequeue_done, instead of resetting all fc_lengths to 0, we only reduced them by U32_MAX / 4 to avoid a moment of imbalance in the scheduling, as Marcelo suggested. Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Signed-off-by: Paolo Abeni --- net/sctp/stream_sched.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/sctp/stream_sched.c') diff --git a/net/sctp/stream_sched.c b/net/sctp/stream_sched.c index 330067002deb..1ebd14ef8daa 100644 --- a/net/sctp/stream_sched.c +++ b/net/sctp/stream_sched.c @@ -124,6 +124,7 @@ void sctp_sched_ops_init(void) sctp_sched_ops_fcfs_init(); sctp_sched_ops_prio_init(); sctp_sched_ops_rr_init(); + sctp_sched_ops_fc_init(); } static void sctp_sched_free_sched(struct sctp_stream *stream) -- cgit v1.2.3