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tcp: add max_quickacks param to tcp_incr_quickack and tcp_enter_quick…
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…ack_mode

[ Upstream commit 9a9c9b5 ]

We want to add finer control of the number of ACK packets sent after
ECN events.

This patch is not changing current behavior, it only enables following
change.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Eric Dumazet authored and Greg Kroah-Hartman committed Aug 6, 2018
1 parent e2f337e commit 2b30c04
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Showing 3 changed files with 16 additions and 14 deletions.
2 changes: 1 addition & 1 deletion include/net/tcp.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -376,7 +376,7 @@ ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags);

void tcp_enter_quickack_mode(struct sock *sk);
void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks);
static inline void tcp_dec_quickack_mode(struct sock *sk,
const unsigned int pkts)
{
Expand Down
4 changes: 2 additions & 2 deletions net/ipv4/tcp_dctcp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -138,7 +138,7 @@ static void dctcp_ce_state_0_to_1(struct sock *sk)
*/
if (inet_csk(sk)->icsk_ack.pending & ICSK_ACK_TIMER)
__tcp_send_ack(sk, ca->prior_rcv_nxt);
tcp_enter_quickack_mode(sk);
tcp_enter_quickack_mode(sk, 1);
}

ca->prior_rcv_nxt = tp->rcv_nxt;
Expand All @@ -159,7 +159,7 @@ static void dctcp_ce_state_1_to_0(struct sock *sk)
*/
if (inet_csk(sk)->icsk_ack.pending & ICSK_ACK_TIMER)
__tcp_send_ack(sk, ca->prior_rcv_nxt);
tcp_enter_quickack_mode(sk);
tcp_enter_quickack_mode(sk, 1);
}

ca->prior_rcv_nxt = tp->rcv_nxt;
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24 changes: 13 additions & 11 deletions net/ipv4/tcp_input.c
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Original file line number Diff line number Diff line change
Expand Up @@ -176,21 +176,23 @@ static void tcp_measure_rcv_mss(struct sock *sk, const struct sk_buff *skb)
}
}

static void tcp_incr_quickack(struct sock *sk)
static void tcp_incr_quickack(struct sock *sk, unsigned int max_quickacks)
{
struct inet_connection_sock *icsk = inet_csk(sk);
unsigned int quickacks = tcp_sk(sk)->rcv_wnd / (2 * icsk->icsk_ack.rcv_mss);

if (quickacks == 0)
quickacks = 2;
quickacks = min(quickacks, max_quickacks);
if (quickacks > icsk->icsk_ack.quick)
icsk->icsk_ack.quick = min(quickacks, TCP_MAX_QUICKACKS);
icsk->icsk_ack.quick = quickacks;
}

void tcp_enter_quickack_mode(struct sock *sk)
void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks)
{
struct inet_connection_sock *icsk = inet_csk(sk);
tcp_incr_quickack(sk);

tcp_incr_quickack(sk, max_quickacks);
icsk->icsk_ack.pingpong = 0;
icsk->icsk_ack.ato = TCP_ATO_MIN;
}
Expand Down Expand Up @@ -235,15 +237,15 @@ static void __tcp_ecn_check_ce(struct tcp_sock *tp, const struct sk_buff *skb)
* it is probably a retransmit.
*/
if (tp->ecn_flags & TCP_ECN_SEEN)
tcp_enter_quickack_mode((struct sock *)tp);
tcp_enter_quickack_mode((struct sock *)tp, TCP_MAX_QUICKACKS);
break;
case INET_ECN_CE:
if (tcp_ca_needs_ecn((struct sock *)tp))
tcp_ca_event((struct sock *)tp, CA_EVENT_ECN_IS_CE);

if (!(tp->ecn_flags & TCP_ECN_DEMAND_CWR)) {
/* Better not delay acks, sender can have a very low cwnd */
tcp_enter_quickack_mode((struct sock *)tp);
tcp_enter_quickack_mode((struct sock *)tp, TCP_MAX_QUICKACKS);
tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
}
tp->ecn_flags |= TCP_ECN_SEEN;
Expand Down Expand Up @@ -651,7 +653,7 @@ static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
/* The _first_ data packet received, initialize
* delayed ACK engine.
*/
tcp_incr_quickack(sk);
tcp_incr_quickack(sk, TCP_MAX_QUICKACKS);
icsk->icsk_ack.ato = TCP_ATO_MIN;
} else {
int m = now - icsk->icsk_ack.lrcvtime;
Expand All @@ -667,7 +669,7 @@ static void tcp_event_data_recv(struct sock *sk, struct sk_buff *skb)
/* Too long gap. Apparently sender failed to
* restart window, so that we send ACKs quickly.
*/
tcp_incr_quickack(sk);
tcp_incr_quickack(sk, TCP_MAX_QUICKACKS);
sk_mem_reclaim(sk);
}
}
Expand Down Expand Up @@ -4136,7 +4138,7 @@ static void tcp_send_dupack(struct sock *sk, const struct sk_buff *skb)
if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
before(TCP_SKB_CB(skb)->seq, tp->rcv_nxt)) {
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_DELAYEDACKLOST);
tcp_enter_quickack_mode(sk);
tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS);

if (tcp_is_sack(tp) && sysctl_tcp_dsack) {
u32 end_seq = TCP_SKB_CB(skb)->end_seq;
Expand Down Expand Up @@ -4638,7 +4640,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
tcp_dsack_set(sk, TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq);

out_of_window:
tcp_enter_quickack_mode(sk);
tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS);
inet_csk_schedule_ack(sk);
drop:
__kfree_skb(skb);
Expand Down Expand Up @@ -5674,7 +5676,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
* to stand against the temptation 8) --ANK
*/
inet_csk_schedule_ack(sk);
tcp_enter_quickack_mode(sk);
tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS);
inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
TCP_DELACK_MAX, TCP_RTO_MAX);

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