diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 1c4597b2c6cdbd163aad37bf49df8d105ebd8f14..b13754a6dd7ac0fff530a71154a5677e22479269 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -255,6 +255,7 @@ struct rxrpc_peer {
 
 	/* calculated RTT cache */
 #define RXRPC_RTT_CACHE_SIZE 32
+	ktime_t			rtt_last_req;	/* Time of last RTT request */
 	u64			rtt;		/* Current RTT estimate (in nS) */
 	u64			rtt_sum;	/* Sum of cache contents */
 	u64			rtt_cache[RXRPC_RTT_CACHE_SIZE]; /* Determined RTT cache */
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index db01fbb70d23cbd7ad4c237336bd31ce002155a5..282cb1e36d061175e64ca09006a17184812cdc05 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -270,6 +270,12 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb)
 	msg.msg_controllen = 0;
 	msg.msg_flags = 0;
 
+	/* If our RTT cache needs working on, request an ACK. */
+	if ((call->peer->rtt_usage < 3 && sp->hdr.seq & 1) ||
+	    ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000),
+			 ktime_get_real()))
+		whdr.flags |= RXRPC_REQUEST_ACK;
+
 	if (IS_ENABLED(CONFIG_AF_RXRPC_INJECT_LOSS)) {
 		static int lose;
 		if ((lose++ & 7) == 7) {
@@ -301,11 +307,14 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb)
 
 done:
 	if (ret >= 0) {
-		skb->tstamp = ktime_get_real();
+		ktime_t now = ktime_get_real();
+		skb->tstamp = now;
 		smp_wmb();
 		sp->hdr.serial = serial;
-		if (whdr.flags & RXRPC_REQUEST_ACK)
+		if (whdr.flags & RXRPC_REQUEST_ACK) {
+			call->peer->rtt_last_req = now;
 			trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_data, serial);
+		}
 	}
 	_leave(" = %d [%u]", ret, call->peer->maxdata);
 	return ret;
diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c
index f3e5766910fd6954052890f0c2b18927d90c64bf..941b724d523bf282e5f8e6901a882c0d12effa0b 100644
--- a/net/rxrpc/peer_object.c
+++ b/net/rxrpc/peer_object.c
@@ -244,6 +244,7 @@ static void rxrpc_init_peer(struct rxrpc_peer *peer, unsigned long hash_key)
 	peer->hash_key = hash_key;
 	rxrpc_assess_MTU_size(peer);
 	peer->mtu = peer->if_mtu;
+	peer->rtt_last_req = ktime_get_real();
 
 	switch (peer->srx.transport.family) {
 	case AF_INET:
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 607223f4f871fe724d93d1b51bb379d6e130e71c..ca7c3be60ad279628c5706c3dfb167c62bbdc234 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -299,8 +299,6 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
 			else if (call->tx_top - call->tx_hard_ack <
 				 call->tx_winsize)
 				sp->hdr.flags |= RXRPC_MORE_PACKETS;
-			if (seq & 1)
-				sp->hdr.flags |= RXRPC_REQUEST_ACK;
 
 			ret = conn->security->secure_packet(
 				call, skb, skb->mark, skb->head);