Commit ca057051 authored by Wei Wang's avatar Wei Wang Committed by David S. Miller
Browse files

tcp: adjust sndbuf according to sk_reserved_mem 



If user sets SO_RESERVE_MEM socket option, in order to fully utilize the
reserved memory in memory pressure state on the tx path, we modify the
logic in sk_stream_moderate_sndbuf() to set sk_sndbuf according to
available reserved memory, instead of MIN_SOCK_SNDBUF, and adjust it
when new data is acked.

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 2bb2f5fb

include/net/sock.h

+1 −0
Original line number Diff line number Diff line
@@ -2378,6 +2378,7 @@ static inline void sk_stream_moderate_sndbuf(struct sock *sk) 
		return;



	val = min(sk->sk_sndbuf, sk->sk_wmem_queued >> 1);

	val = max_t(u32, val, sk_unused_reserved_mem(sk));



	WRITE_ONCE(sk->sk_sndbuf, max_t(u32, val, SOCK_MIN_SNDBUF));

}

net/ipv4/tcp_input.c

+12 −2
Original line number Diff line number Diff line
@@ -5380,7 +5380,7 @@ static int tcp_prune_queue(struct sock *sk) 
	return -1;

}



static bool tcp_should_expand_sndbuf(const struct sock *sk)

static bool tcp_should_expand_sndbuf(struct sock *sk)

{

	const struct tcp_sock *tp = tcp_sk(sk);
@@ -5391,8 +5391,18 @@ static bool tcp_should_expand_sndbuf(const struct sock *sk) 
		return false;



	/* If we are under global TCP memory pressure, do not expand.  */

	if (tcp_under_memory_pressure(sk))

	if (tcp_under_memory_pressure(sk)) {

		int unused_mem = sk_unused_reserved_mem(sk);



		/* Adjust sndbuf according to reserved mem. But make sure

		 * it never goes below SOCK_MIN_SNDBUF.

		 * See sk_stream_moderate_sndbuf() for more details.

		 */

		if (unused_mem > SOCK_MIN_SNDBUF)

			WRITE_ONCE(sk->sk_sndbuf, unused_mem);



		return false;

	}



	/* If we are under soft global TCP memory pressure, do not expand.  */

	if (sk_memory_allocated(sk) >= sk_prot_mem_limits(sk, 0))