netdev - Re: [PATCH net 2/2] tcp: remove DELAYED ACK events in DCTCP

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Message-ID: <05812175-8319-4D7D-9770-B85D963BD8B0@fb.com>
Date:   Thu, 12 Jul 2018 13:09:47 +0000
From:   Lawrence Brakmo <brakmo@...com>
To:     Yuchung Cheng <ycheng@...gle.com>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "ncardwell@...gle.com" <ncardwell@...gle.com>,
        "ysseung@...gle.com" <ysseung@...gle.com>,
        "edumazet@...gle.com" <edumazet@...gle.com>
Subject: Re: [PATCH net 2/2] tcp: remove DELAYED ACK events in DCTCP

LGTM. Thanks for the patch.

Acked-by: Lawrence Brakmo <brakmo@...com>

On 7/12/18, 9:05 AM, "Yuchung Cheng" <ycheng@...gle.com> wrote:

    After fixing the way DCTCP tracking delayed ACKs, the delayed-ACK
    related callbacks are no longer needed
    
    Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
    Signed-off-by: Eric Dumazet <edumazet@...gle.com>
    Acked-by: Neal Cardwell <ncardwell@...gle.com>
    ---
     include/net/tcp.h     |  2 --
     net/ipv4/tcp_dctcp.c  | 25 -------------------------
     net/ipv4/tcp_output.c |  4 ----
     3 files changed, 31 deletions(-)
    
    diff --git a/include/net/tcp.h b/include/net/tcp.h
    index af3ec72d5d41..3482d13d655b 100644
    --- a/include/net/tcp.h
    +++ b/include/net/tcp.h
    @@ -912,8 +912,6 @@ enum tcp_ca_event {
     	CA_EVENT_LOSS,		/* loss timeout */
     	CA_EVENT_ECN_NO_CE,	/* ECT set, but not CE marked */
     	CA_EVENT_ECN_IS_CE,	/* received CE marked IP packet */
    -	CA_EVENT_DELAYED_ACK,	/* Delayed ack is sent */
    -	CA_EVENT_NON_DELAYED_ACK,
     };
     
     /* Information about inbound ACK, passed to cong_ops->in_ack_event() */
    diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c
    index 89f88b0d8167..5869f89ca656 100644
    --- a/net/ipv4/tcp_dctcp.c
    +++ b/net/ipv4/tcp_dctcp.c
    @@ -55,7 +55,6 @@ struct dctcp {
     	u32 dctcp_alpha;
     	u32 next_seq;
     	u32 ce_state;
    -	u32 delayed_ack_reserved;
     	u32 loss_cwnd;
     };
     
    @@ -96,7 +95,6 @@ static void dctcp_init(struct sock *sk)
     
     		ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA);
     
    -		ca->delayed_ack_reserved = 0;
     		ca->loss_cwnd = 0;
     		ca->ce_state = 0;
     
    @@ -250,25 +248,6 @@ static void dctcp_state(struct sock *sk, u8 new_state)
     	}
     }
     
    -static void dctcp_update_ack_reserved(struct sock *sk, enum tcp_ca_event ev)
    -{
    -	struct dctcp *ca = inet_csk_ca(sk);
    -
    -	switch (ev) {
    -	case CA_EVENT_DELAYED_ACK:
    -		if (!ca->delayed_ack_reserved)
    -			ca->delayed_ack_reserved = 1;
    -		break;
    -	case CA_EVENT_NON_DELAYED_ACK:
    -		if (ca->delayed_ack_reserved)
    -			ca->delayed_ack_reserved = 0;
    -		break;
    -	default:
    -		/* Don't care for the rest. */
    -		break;
    -	}
    -}
    -
     static void dctcp_cwnd_event(struct sock *sk, enum tcp_ca_event ev)
     {
     	switch (ev) {
    @@ -278,10 +257,6 @@ static void dctcp_cwnd_event(struct sock *sk, enum tcp_ca_event ev)
     	case CA_EVENT_ECN_NO_CE:
     		dctcp_ce_state_1_to_0(sk);
     		break;
    -	case CA_EVENT_DELAYED_ACK:
    -	case CA_EVENT_NON_DELAYED_ACK:
    -		dctcp_update_ack_reserved(sk, ev);
    -		break;
     	default:
     		/* Don't care for the rest. */
     		break;
    diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
    index 8e08b409c71e..00e5a300ddb9 100644
    --- a/net/ipv4/tcp_output.c
    +++ b/net/ipv4/tcp_output.c
    @@ -3523,8 +3523,6 @@ void tcp_send_delayed_ack(struct sock *sk)
     	int ato = icsk->icsk_ack.ato;
     	unsigned long timeout;
     
    -	tcp_ca_event(sk, CA_EVENT_DELAYED_ACK);
    -
     	if (ato > TCP_DELACK_MIN) {
     		const struct tcp_sock *tp = tcp_sk(sk);
     		int max_ato = HZ / 2;
    @@ -3581,8 +3579,6 @@ void tcp_send_ack(struct sock *sk)
     	if (sk->sk_state == TCP_CLOSE)
     		return;
     
    -	tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK);
    -
     	/* We are not putting this on the write queue, so
     	 * tcp_transmit_skb() will set the ownership to this
     	 * sock.
    -- 
    2.18.0.203.gfac676dfb9-goog