From: Eric Dumazet <[email protected]> At enqueue time, check sojourn time of packet at head of the queue, and return NET_XMIT_CN instead of NET_XMIT_SUCCESS if this sejourn time is above codel @target.
This permits local TCP stack to call tcp_enter_cwr() and reduce its cwnd without drops (for example if ECN is not enabled for the flow) Signed-off-by: Eric Dumazet <[email protected]> Cc: Dave Taht <[email protected]> Cc: Tom Herbert <[email protected]> Cc: Matt Mathis <[email protected]> Cc: Yuchung Cheng <[email protected]> Cc: Nandita Dukkipati <[email protected]> Cc: Neal Cardwell <[email protected]> --- include/linux/pkt_sched.h | 1 + include/net/codel.h | 2 +- net/sched/sch_fq_codel.c | 19 +++++++++++++++---- 3 files changed, 17 insertions(+), 5 deletions(-) diff --git a/include/linux/pkt_sched.h b/include/linux/pkt_sched.h index 32aef0a..4d409a5 100644 --- a/include/linux/pkt_sched.h +++ b/include/linux/pkt_sched.h @@ -714,6 +714,7 @@ struct tc_fq_codel_qd_stats { */ __u32 new_flows_len; /* count of flows in new list */ __u32 old_flows_len; /* count of flows in old list */ + __u32 congestion_count; }; struct tc_fq_codel_cl_stats { diff --git a/include/net/codel.h b/include/net/codel.h index 550debf..8c7d6a7 100644 --- a/include/net/codel.h +++ b/include/net/codel.h @@ -148,7 +148,7 @@ struct codel_vars { * struct codel_stats - contains codel shared variables and stats * @maxpacket: largest packet we've seen so far * @drop_count: temp count of dropped packets in dequeue() - * ecn_mark: number of packets we ECN marked instead of dropping + * @ecn_mark: number of packets we ECN marked instead of dropping */ struct codel_stats { u32 maxpacket; diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c index 9fc1c62..c0485a0 100644 --- a/net/sched/sch_fq_codel.c +++ b/net/sched/sch_fq_codel.c @@ -62,6 +62,7 @@ struct fq_codel_sched_data { struct codel_stats cstats; u32 drop_overlimit; u32 new_flow_count; + u32 congestion_count; struct list_head new_flows; /* list of new flows */ struct list_head old_flows; /* list of old flows */ @@ -196,16 +197,25 @@ static int fq_codel_enqueue(struct sk_buff *skb, struct Qdisc *sch) flow->deficit = q->quantum; flow->dropped = 0; } - if (++sch->q.qlen < sch->limit) + if (++sch->q.qlen < sch->limit) { + codel_time_t hdelay = codel_get_enqueue_time(skb) - + codel_get_enqueue_time(flow->head); + + /* If this flow is congested, tell the caller ! */ + if (codel_time_after(hdelay, q->cparams.target)) { + q->congestion_count++; + return NET_XMIT_CN; + } return NET_XMIT_SUCCESS; - + } q->drop_overlimit++; /* Return Congestion Notification only if we dropped a packet * from this flow. */ - if (fq_codel_drop(sch) == idx) + if (fq_codel_drop(sch) == idx) { + q->congestion_count++; return NET_XMIT_CN; - + } /* As we dropped a packet, better let upper stack know this */ qdisc_tree_decrease_qlen(sch, 1); return NET_XMIT_SUCCESS; @@ -467,6 +477,7 @@ static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d) st.qdisc_stats.maxpacket = q->cstats.maxpacket; st.qdisc_stats.drop_overlimit = q->drop_overlimit; + st.qdisc_stats.congestion_count = q->congestion_count; st.qdisc_stats.ecn_mark = q->cstats.ecn_mark; st.qdisc_stats.new_flow_count = q->new_flow_count; _______________________________________________ Codel mailing list [email protected] https://lists.bufferbloat.net/listinfo/codel
