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tcp: tcp_cong_control helper 

Refactor and consolidate cwnd and rate updates into a new function
tcp_cong_control().

Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yuchung Cheng 2016-02-02 10:33:09 -08:00 committed by David S. Miller
parent 2d14a4def4
commit d452e6caf8
1 changed files with 19 additions and 12 deletions
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31
net/ipv4/tcp_input.c
View File

@ -3323,6 +3323,24 @@ static inline bool tcp_may_raise_cwnd(const struct sock *sk, const int flag)
return flag & FLAG_DATA_ACKED;
}
/* The "ultimate" congestion control function that aims to replace the rigid
* cwnd increase and decrease control (tcp_cong_avoid,tcp_*cwnd_reduction).
* It's called toward the end of processing an ACK with precise rate
* information. All transmission or retransmission are delayed afterwards.
*/
static void tcp_cong_control(struct sock *sk, u32 ack, u32 acked_sacked,
int flag)
{
if (tcp_in_cwnd_reduction(sk)) {
/* Reduce cwnd if state mandates */
tcp_cwnd_reduction(sk, acked_sacked, flag);
} else if (tcp_may_raise_cwnd(sk, flag)) {
/* Advance cwnd if state allows */
tcp_cong_avoid(sk, ack, acked_sacked);
}
tcp_update_pacing_rate(sk);
}
/* Check that window update is acceptable.
* The function assumes that snd_una<=ack<=snd_next.
*/
@ -3553,7 +3571,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
int prior_packets = tp->packets_out;
u32 prior_delivered = tp->delivered;
int acked = 0; /* Number of packets newly acked */
u32 acked_sacked; /* Number of packets newly acked or sacked */
int rexmit = REXMIT_NONE; /* Flag to (re)transmit to recover losses */
sack_state.first_sackt.v64 = 0;
@ -3653,16 +3670,6 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
if (tp->tlp_high_seq)
tcp_process_tlp_ack(sk, ack, flag);
acked_sacked = tp->delivered - prior_delivered;
/* Advance cwnd if state allows */
if (tcp_in_cwnd_reduction(sk)) {
/* Reduce cwnd if state mandates */
tcp_cwnd_reduction(sk, acked_sacked, flag);
} else if (tcp_may_raise_cwnd(sk, flag)) {
/* Advance cwnd if state allows */
tcp_cong_avoid(sk, ack, acked_sacked);
}
if ((flag & FLAG_FORWARD_PROGRESS) || !(flag & FLAG_NOT_DUP)) {
struct dst_entry *dst = __sk_dst_get(sk);
if (dst)
@ -3671,7 +3678,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
if (icsk->icsk_pending == ICSK_TIME_RETRANS)
tcp_schedule_loss_probe(sk);
tcp_update_pacing_rate(sk);
tcp_cong_control(sk, ack, tp->delivered - prior_delivered, flag);
tcp_xmit_recovery(sk, rexmit);
return 1;