From 2c13c05c5ff4b9fc907b07f7311821910ebaaf8a Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 21 Jan 2022 23:12:58 +0000 Subject: rxrpc: Adjust retransmission backoff 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 Signed-off-by: David Howells Reviewed-by: Marc Dionne Tested-by: Marc Dionne cc: linux-afs@lists.infradead.org Link: https://lore.kernel.org/r/164138117069.2023386.17446904856843997127.stgit@warthog.procyon.org.uk/ Signed-off-by: David S. Miller --- net/rxrpc/output.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/rxrpc/output.c') diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index 10f2bf2e9068..a45c83f22236 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, -- cgit v1.2.3-59-g8ed1b