From: David Howells dhowells@redhat.com
[ 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@auristor.com Signed-off-by: David Howells dhowells@redhat.com Reviewed-by: Marc Dionne marc.dionne@auristor.com Tested-by: Marc Dionne marc.dionne@auristor.com cc: linux-afs@lists.infradead.org Link: https://lore.kernel.org/r/164138117069.2023386.17446904856843997127.stgit@wa... Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/rxrpc/call_event.c | 8 +++----- net/rxrpc/output.c | 2 +- 2 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c index 6be2672a65eab..df864e6922679 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 10f2bf2e9068a..a45c83f22236e 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -468,7 +468,7 @@ done: 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,