This is a note to let you know that I've just added the patch titled
rxrpc: Adjust retransmission backoff
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rxrpc-adjust-retransmission-backoff.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 18d943cc781d4fbeb06464ef10488ade298c3186
Author: David Howells <dhowells@xxxxxxxxxx>
Date: Fri Jan 21 23:12:58 2022 +0000
rxrpc: Adjust retransmission backoff
[ Upstream commit 2c13c05c5ff4b9fc907b07f7311821910ebaaf8a ]
Improve retransmission backoff by only backing off when we retransmit data
packets rather than when we set the lost ack timer.
To this end:
(1) In rxrpc_resend(), use rxrpc_get_rto_backoff() when setting the
retransmission timer and only tell it that we are retransmitting if we
actually have things to retransmit.
Note that it's possible for the retransmission algorithm to race with
the processing of a received ACK, so we may see no packets needing
retransmission.
(2) In rxrpc_send_data_packet(), don't bump the backoff when setting the
ack_lost_at timer, as it may then get bumped twice.
With this, when looking at one particular packet, the retransmission
intervals were seen to be 1.5ms, 2ms, 3ms, 5ms, 9ms, 17ms, 33ms, 71ms,
136ms, 264ms, 544ms, 1.088s, 2.1s, 4.2s and 8.3s.
Fixes: c410bf01933e ("rxrpc: Fix the excessive initial retransmission timeout")
Suggested-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Reviewed-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
Tested-by: Marc Dionne <marc.dionne@xxxxxxxxxxxx>
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/164138117069.2023386.17446904856843997127.stgit@xxxxxxxxxxxxxxxxxxxxxx/
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
index 9ff85ee8337cd..80e15310f1b29 100644
--- a/net/rxrpc/call_event.c
+++ b/net/rxrpc/call_event.c
@@ -157,7 +157,7 @@ static void rxrpc_congestion_timeout(struct rxrpc_call *call)
static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
{
struct sk_buff *skb;
- unsigned long resend_at, rto_j;
+ unsigned long resend_at;
rxrpc_seq_t cursor, seq, top;
ktime_t now, max_age, oldest, ack_ts;
int ix;
@@ -165,10 +165,8 @@ static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
_enter("{%d,%d}", call->tx_hard_ack, call->tx_top);
- rto_j = call->peer->rto_j;
-
now = ktime_get_real();
- max_age = ktime_sub(now, jiffies_to_usecs(rto_j));
+ max_age = ktime_sub(now, jiffies_to_usecs(call->peer->rto_j));
spin_lock_bh(&call->lock);
@@ -213,7 +211,7 @@ static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j)
}
resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest)));
- resend_at += jiffies + rto_j;
+ resend_at += jiffies + rxrpc_get_rto_backoff(call->peer, retrans);
WRITE_ONCE(call->resend_at, resend_at);
if (unacked)
diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index f8b632a5c6197..a4a6f8ee07201 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -426,7 +426,7 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb,
if (call->peer->rtt_count > 1) {
unsigned long nowj = jiffies, ack_lost_at;
- ack_lost_at = rxrpc_get_rto_backoff(call->peer, retrans);
+ ack_lost_at = rxrpc_get_rto_backoff(call->peer, false);
ack_lost_at += nowj;
WRITE_ONCE(call->ack_lost_at, ack_lost_at);
rxrpc_reduce_call_timer(call, ack_lost_at, nowj,
