Commit 053f3684 authored by Wei Wang's avatar Wei Wang Committed by David S. Miller
Browse files

tcp: adjust rcv_ssthresh according to sk_reserved_mem 



When user sets SO_RESERVE_MEM socket option, in order to utilize the
reserved memory when in memory pressure state, we adjust rcv_ssthresh
according to the available reserved memory for the socket, instead of
using 4 * advmss always.

Signed-off-by: default avatarWei Wang <weiwan@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ca057051

include/net/tcp.h

+11 −0
Original line number Diff line number Diff line
@@ -1421,6 +1421,17 @@ static inline int tcp_full_space(const struct sock *sk) 
	return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));

}



static inline void tcp_adjust_rcv_ssthresh(struct sock *sk)

{

	int unused_mem = sk_unused_reserved_mem(sk);

	struct tcp_sock *tp = tcp_sk(sk);



	tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);

	if (unused_mem)

		tp->rcv_ssthresh = max_t(u32, tp->rcv_ssthresh,

					 tcp_win_from_space(sk, unused_mem));

}



void tcp_cleanup_rbuf(struct sock *sk, int copied);



/* We provision sk_rcvbuf around 200% of sk_rcvlowat.

net/ipv4/tcp_input.c

+10 −2
Original line number Diff line number Diff line
@@ -500,8 +500,11 @@ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb, 


	room = min_t(int, tp->window_clamp, tcp_space(sk)) - tp->rcv_ssthresh;



	if (room <= 0)

		return;



	/* Check #1 */

	if (room > 0 && !tcp_under_memory_pressure(sk)) {

	if (!tcp_under_memory_pressure(sk)) {

		unsigned int truesize = truesize_adjust(adjust, skb);

		int incr;
@@ -518,6 +521,11 @@ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb, 
			tp->rcv_ssthresh += min(room, incr);

			inet_csk(sk)->icsk_ack.quick |= 1;

		}

	} else {

		/* Under pressure:

		 * Adjust rcv_ssthresh according to reserved mem

		 */

		tcp_adjust_rcv_ssthresh(sk);

	}

}
@@ -5345,7 +5353,7 @@ static int tcp_prune_queue(struct sock *sk) 
	if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)

		tcp_clamp_window(sk);

	else if (tcp_under_memory_pressure(sk))

		tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);

		tcp_adjust_rcv_ssthresh(sk);



	if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)

		return 0;

net/ipv4/tcp_output.c

+1 −2
Original line number Diff line number Diff line
@@ -2967,8 +2967,7 @@ u32 __tcp_select_window(struct sock *sk) 
		icsk->icsk_ack.quick = 0;



		if (tcp_under_memory_pressure(sk))

			tp->rcv_ssthresh = min(tp->rcv_ssthresh,

					       4U * tp->advmss);

			tcp_adjust_rcv_ssthresh(sk);



		/* free_space might become our new window, make sure we don't

		 * increase it due to wscale.