netdev - [PATCH net-next 07/12] rxrpc: Don't transmit DELAY ACKs immediately on proposal

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Date:   Fri, 24 Nov 2017 14:38:27 +0000
From:   David Howells <dhowells@...hat.com>
To:     netdev@...r.kernel.org
Cc:     dhowells@...hat.com, linux-afs@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next 07/12] rxrpc: Don't transmit DELAY ACKs immediately
 on proposal

Don't transmit a DELAY ACK immediately on proposal when the Rx window is
rotated, but rather defer it to the work function.  This means that we have
a chance to queue/consume more received packets before we actually send the
DELAY ACK, or even cancel it entirely, thereby reducing the number of
packets transmitted.

We do, however, want to continue sending other types of packet immediately,
particularly REQUESTED ACKs, as they may be used for RTT calculation by the
other side.

Signed-off-by: David Howells <dhowells@...hat.com>
---

 net/rxrpc/recvmsg.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index 0b6609da80b7..fad5f42a3abd 100644
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -219,9 +219,9 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
 		    after_eq(top, call->ackr_seen + 2) ||
 		    (hard_ack == top && after(hard_ack, call->ackr_consumed)))
 			rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, 0, serial,
-					  true, false,
+					  true, true,
 					  rxrpc_propose_ack_rotate_rx);
-		if (call->ackr_reason)
+		if (call->ackr_reason && call->ackr_reason != RXRPC_ACK_DELAY)
 			rxrpc_send_ack_packet(call, false);
 	}
 }