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Commit f9c7ce18 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'tcp-tso' 



Eric Dumazet says:

====================
tcp: tso improvements

This patch serie reworks tcp_tso_should_defer() a bit
to get less bursts, and better ECN behavior.

We also removed tso_deferred field in tcp socket.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 6588af61 a0ea700e

include/linux/tcp.h

+0 −1
Original line number Diff line number Diff line
@@ -236,7 +236,6 @@ struct tcp_sock { 
	u32	lost_out;	/* Lost packets			*/

	u32	sacked_out;	/* SACK'd packets			*/

	u32	fackets_out;	/* FACK'd packets			*/

	u32	tso_deferred;



	/* from STCP, retrans queue hinting */

	struct sk_buff* lost_skb_hint;

net/ipv4/tcp_output.c

+17 −12
Original line number Diff line number Diff line
@@ -1752,20 +1752,23 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len, 
static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb,

				 bool *is_cwnd_limited, u32 max_segs)

{

	struct tcp_sock *tp = tcp_sk(sk);

	const struct inet_connection_sock *icsk = inet_csk(sk);

	u32 send_win, cong_win, limit, in_flight;

	u32 age, send_win, cong_win, limit, in_flight;

	struct tcp_sock *tp = tcp_sk(sk);

	struct skb_mstamp now;

	struct sk_buff *head;

	int win_divisor;



	if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_FIN)

		goto send_now;



	if (icsk->icsk_ca_state != TCP_CA_Open)

	if (!((1 << icsk->icsk_ca_state) & (TCPF_CA_Open | TCPF_CA_CWR)))

		goto send_now;



	/* Defer for less than two clock ticks. */

	if (tp->tso_deferred &&

	    (((u32)jiffies << 1) >> 1) - (tp->tso_deferred >> 1) > 1)

	/* Avoid bursty behavior by allowing defer

	 * only if the last write was recent.

	 */

	if ((s32)(tcp_time_stamp - tp->lsndtime) > 0)

		goto send_now;



	in_flight = tcp_packets_in_flight(tp);
@@ -1807,11 +1810,14 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 
			goto send_now;

	}



	/* Ok, it looks like it is advisable to defer.

	 * Do not rearm the timer if already set to not break TCP ACK clocking.

	 */

	if (!tp->tso_deferred)

		tp->tso_deferred = 1 | (jiffies << 1);

	head = tcp_write_queue_head(sk);

	skb_mstamp_get(&now);

	age = skb_mstamp_us_delta(&now, &head->skb_mstamp);

	/* If next ACK is likely to come too late (half srtt), do not defer */

	if (age < (tp->srtt_us >> 4))

		goto send_now;



	/* Ok, it looks like it is advisable to defer. */



	if (cong_win < send_win && cong_win < skb->len)

		*is_cwnd_limited = true;
@@ -1819,7 +1825,6 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb, 
	return true;



send_now:

	tp->tso_deferred = 0;

	return false;

}