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Commit 4929c942 authored Jul 09, 2018 by Deepti Raghavan Committed by David S. Miller Jul 11, 2018

tcp: expose both send and receive intervals for rate sample



Congestion control algorithms, which access the rate sample
through the tcp_cong_control function, only have access to the maximum
of the send and receive interval, for cases where the acknowledgment
rate may be inaccurate due to ACK compression or decimation. Algorithms
may want to use send rates and receive rates as separate signals.

Signed-off-by: Deepti Raghavan <deeptir@mit.edu>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent e0479b67

include/net/tcp.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -954,6 +954,8 @@ struct rate_sample {
		u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
		s32 delivered; /* number of packets delivered over interval */
		long interval_us; /* time for tp->delivered to incr "delivered" */
		u32 snd_interval_us; /* snd interval for delivered packets */
		u32 rcv_interval_us; /* rcv interval for delivered packets */
		long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
		int losses; /* number of packets marked lost upon ACK */
		u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */

net/ipv4/tcp_rate.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -146,6 +146,10 @@ void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
		rs->prior_mstamp); /* ack phase */
		rs->interval_us = max(snd_us, ack_us);

		/* Record both segment send and ack receive intervals */
		rs->snd_interval_us = snd_us;
		rs->rcv_interval_us = ack_us;

		/* Normally we expect interval_us >= min-rtt.
		* Note that rate may still be over-estimated when a spuriously
		* retransmistted skb was first (s)acked because "interval_us"