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tcp: adjust rcv_ssthresh according to sk_reserved_mem

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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: Wei Wang <weiwan@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wei Wang 2021-09-29 10:25:13 -07:00 committed by David S. Miller
parent ca057051cf
commit 053f368412
3 changed files with 22 additions and 4 deletions
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11
include/net/tcp.h
View File

@ -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)); 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); void tcp_cleanup_rbuf(struct sock *sk, int copied);
/* We provision sk_rcvbuf around 200% of sk_rcvlowat. /* We provision sk_rcvbuf around 200% of sk_rcvlowat.

12
net/ipv4/tcp_input.c
View File

@ -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; room = min_t(int, tp->window_clamp, tcp_space(sk)) - tp->rcv_ssthresh;
if (room <= 0)
return;
/* Check #1 */ /* Check #1 */
if (room > 0 && !tcp_under_memory_pressure(sk)) { if (!tcp_under_memory_pressure(sk)) {
unsigned int truesize = truesize_adjust(adjust, skb); unsigned int truesize = truesize_adjust(adjust, skb);
int incr; 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); tp->rcv_ssthresh += min(room, incr);
inet_csk(sk)->icsk_ack.quick |= 1; 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) if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
tcp_clamp_window(sk); tcp_clamp_window(sk);
else if (tcp_under_memory_pressure(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) if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)
return 0; return 0;

3
net/ipv4/tcp_output.c
View File

@ -2967,8 +2967,7 @@ u32 __tcp_select_window(struct sock *sk)
icsk->icsk_ack.quick = 0; icsk->icsk_ack.quick = 0;
if (tcp_under_memory_pressure(sk)) if (tcp_under_memory_pressure(sk))
tp->rcv_ssthresh = min(tp->rcv_ssthresh, tcp_adjust_rcv_ssthresh(sk);
4U * tp->advmss);
/* free_space might become our new window, make sure we don't /* free_space might become our new window, make sure we don't
* increase it due to wscale. * increase it due to wscale.