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Commit 48d79b49 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'tcp-better-receiver-autotuning' 



Eric Dumazet says:

====================
tcp: better receiver autotuning

Now TCP senders no longer backoff when a drop is detected,
it appears we are very often receive window limited.

This series makes tcp_rcv_space_adjust() slightly more robust
and responsive.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents c360f2b5 c3916ad9

include/linux/tcp.h

+1 −1
Original line number Diff line number Diff line
@@ -344,7 +344,7 @@ struct tcp_sock { 


/* Receiver queue space */

	struct {

		int	space;

		u32	space;

		u32	seq;

		u64	time;

	} rcvq_space;

net/ipv4/tcp_input.c

+12 −19
Original line number Diff line number Diff line
@@ -576,8 +576,8 @@ static inline void tcp_rcv_rtt_measure_ts(struct sock *sk, 
void tcp_rcv_space_adjust(struct sock *sk)

{

	struct tcp_sock *tp = tcp_sk(sk);

	u32 copied;

	int time;

	int copied;



	tcp_mstamp_refresh(tp);

	time = tcp_stamp_us_delta(tp->tcp_mstamp, tp->rcvq_space.time);
@@ -600,38 +600,31 @@ void tcp_rcv_space_adjust(struct sock *sk) 


	if (sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf &&

	    !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {

		int rcvwin, rcvmem, rcvbuf;

		int rcvmem, rcvbuf;

		u64 rcvwin, grow;



		/* minimal window to cope with packet losses, assuming

		 * steady state. Add some cushion because of small variations.

		 */

		rcvwin = (copied << 1) + 16 * tp->advmss;

		rcvwin = ((u64)copied << 1) + 16 * tp->advmss;



		/* If rate increased by 25%,

		 *	assume slow start, rcvwin = 3 * copied

		 * If rate increased by 50%,

		 *	assume sender can use 2x growth, rcvwin = 4 * copied

		 */

		if (copied >=

		    tp->rcvq_space.space + (tp->rcvq_space.space >> 2)) {

			if (copied >=

			    tp->rcvq_space.space + (tp->rcvq_space.space >> 1))

				rcvwin <<= 1;

			else

				rcvwin += (rcvwin >> 1);

		}

		/* Accommodate for sender rate increase (eg. slow start) */

		grow = rcvwin * (copied - tp->rcvq_space.space);

		do_div(grow, tp->rcvq_space.space);

		rcvwin += (grow << 1);



		rcvmem = SKB_TRUESIZE(tp->advmss + MAX_TCP_HEADER);

		while (tcp_win_from_space(sk, rcvmem) < tp->advmss)

			rcvmem += 128;



		rcvbuf = min(rcvwin / tp->advmss * rcvmem,

		do_div(rcvwin, tp->advmss);

		rcvbuf = min_t(u64, rcvwin * rcvmem,

			       sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);

		if (rcvbuf > sk->sk_rcvbuf) {

			sk->sk_rcvbuf = rcvbuf;



			/* Make the window clamp follow along.  */

			tp->window_clamp = rcvwin;

			tp->window_clamp = tcp_win_from_space(sk, rcvbuf);

		}

	}

	tp->rcvq_space.space = copied;