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-rw-r--r--net/ipv4/tcp_input.c84
1 files changed, 53 insertions, 31 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 25a89eaa669d..5d083855c111 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -355,6 +355,12 @@ static void tcp_fixup_rcvbuf(struct sock *sk)
rcvmem = 2 * SKB_TRUESIZE(mss + MAX_TCP_HEADER) *
tcp_default_init_rwnd(mss);
+ /* Dynamic Right Sizing (DRS) has 2 to 3 RTT latency
+ * Allow enough cushion so that sender is not limited by our window
+ */
+ if (sysctl_tcp_moderate_rcvbuf)
+ rcvmem <<= 2;
+
if (sk->sk_rcvbuf < rcvmem)
sk->sk_rcvbuf = min(rcvmem, sysctl_tcp_rmem[2]);
}
@@ -373,6 +379,8 @@ void tcp_init_buffer_space(struct sock *sk)
tcp_fixup_sndbuf(sk);
tp->rcvq_space.space = tp->rcv_wnd;
+ tp->rcvq_space.time = tcp_time_stamp;
+ tp->rcvq_space.seq = tp->copied_seq;
maxwin = tcp_full_space(sk);
@@ -512,48 +520,62 @@ void tcp_rcv_space_adjust(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
int time;
- int space;
-
- if (tp->rcvq_space.time == 0)
- goto new_measure;
+ int copied;
time = tcp_time_stamp - tp->rcvq_space.time;
if (time < (tp->rcv_rtt_est.rtt >> 3) || tp->rcv_rtt_est.rtt == 0)
return;
- space = 2 * (tp->copied_seq - tp->rcvq_space.seq);
+ /* Number of bytes copied to user in last RTT */
+ copied = tp->copied_seq - tp->rcvq_space.seq;
+ if (copied <= tp->rcvq_space.space)
+ goto new_measure;
+
+ /* A bit of theory :
+ * copied = bytes received in previous RTT, our base window
+ * To cope with packet losses, we need a 2x factor
+ * To cope with slow start, and sender growing its cwin by 100 %
+ * every RTT, we need a 4x factor, because the ACK we are sending
+ * now is for the next RTT, not the current one :
+ * <prev RTT . ><current RTT .. ><next RTT .... >
+ */
+
+ if (sysctl_tcp_moderate_rcvbuf &&
+ !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
+ int rcvwin, rcvmem, rcvbuf;
- space = max(tp->rcvq_space.space, space);
+ /* minimal window to cope with packet losses, assuming
+ * steady state. Add some cushion because of small variations.
+ */
+ rcvwin = (copied << 1) + 16 * tp->advmss;
- if (tp->rcvq_space.space != space) {
- int rcvmem;
+ /* 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);
+ }
- tp->rcvq_space.space = space;
+ rcvmem = SKB_TRUESIZE(tp->advmss + MAX_TCP_HEADER);
+ while (tcp_win_from_space(rcvmem) < tp->advmss)
+ rcvmem += 128;
- if (sysctl_tcp_moderate_rcvbuf &&
- !(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
- int new_clamp = space;
+ rcvbuf = min(rcvwin / tp->advmss * rcvmem, sysctl_tcp_rmem[2]);
+ if (rcvbuf > sk->sk_rcvbuf) {
+ sk->sk_rcvbuf = rcvbuf;
- /* Receive space grows, normalize in order to
- * take into account packet headers and sk_buff
- * structure overhead.
- */
- space /= tp->advmss;
- if (!space)
- space = 1;
- rcvmem = SKB_TRUESIZE(tp->advmss + MAX_TCP_HEADER);
- while (tcp_win_from_space(rcvmem) < tp->advmss)
- rcvmem += 128;
- space *= rcvmem;
- space = min(space, sysctl_tcp_rmem[2]);
- if (space > sk->sk_rcvbuf) {
- sk->sk_rcvbuf = space;
-
- /* Make the window clamp follow along. */
- tp->window_clamp = new_clamp;
- }
+ /* Make the window clamp follow along. */
+ tp->window_clamp = rcvwin;
}
}
+ tp->rcvq_space.space = copied;
new_measure:
tp->rcvq_space.seq = tp->copied_seq;
@@ -5674,8 +5696,8 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
tcp_init_congestion_control(sk);
tcp_mtup_init(sk);
- tcp_init_buffer_space(sk);
tp->copied_seq = tp->rcv_nxt;
+ tcp_init_buffer_space(sk);
}
smp_mb();
tcp_set_state(sk, TCP_ESTABLISHED);