From f7aec129a356ad049edddcb7e77b04a474fcf41f Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 14 Jun 2017 17:56:50 +0100 Subject: [PATCH] rxrpc: Cache the congestion window setting Cache the congestion window setting that was determined during a call's transmission phase when it finishes so that it can be used by the next call to the same peer, thereby shortcutting the slow-start algorithm. The value is stored in the rxrpc_peer struct and is accessed without locking. Each call takes the value that happens to be there when it starts and just overwrites the value when it finishes. Signed-off-by: David Howells Signed-off-by: David S. Miller --- net/rxrpc/ar-internal.h | 2 ++ net/rxrpc/call_accept.c | 1 + net/rxrpc/call_object.c | 7 +------ net/rxrpc/conn_client.c | 6 ++++++ net/rxrpc/conn_object.c | 2 ++ net/rxrpc/peer_object.c | 7 +++++++ 6 files changed, 19 insertions(+), 6 deletions(-) diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index adbf37946450..69b97339ff9d 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -300,6 +300,8 @@ struct rxrpc_peer { u64 rtt_cache[RXRPC_RTT_CACHE_SIZE]; /* Determined RTT cache */ u8 rtt_cursor; /* next entry at which to insert */ u8 rtt_usage; /* amount of cache actually used */ + + u8 cong_cwnd; /* Congestion window size */ }; /* diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c index 0d4d84e8c074..dd30d74824b0 100644 --- a/net/rxrpc/call_accept.c +++ b/net/rxrpc/call_accept.c @@ -310,6 +310,7 @@ static struct rxrpc_call *rxrpc_alloc_incoming_call(struct rxrpc_sock *rx, rxrpc_see_call(call); call->conn = conn; call->peer = rxrpc_get_peer(conn->params.peer); + call->cong_cwnd = call->peer->cong_cwnd; return call; } diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c index 423030fd93be..d7809a0620b4 100644 --- a/net/rxrpc/call_object.c +++ b/net/rxrpc/call_object.c @@ -136,12 +136,7 @@ struct rxrpc_call *rxrpc_alloc_call(gfp_t gfp) call->tx_winsize = 16; call->rx_expect_next = 1; - if (RXRPC_TX_SMSS > 2190) - call->cong_cwnd = 2; - else if (RXRPC_TX_SMSS > 1095) - call->cong_cwnd = 3; - else - call->cong_cwnd = 4; + call->cong_cwnd = 2; call->cong_ssthresh = RXRPC_RXTX_BUFF_SIZE - 1; return call; diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c index dd8bb919c15a..eb2157680399 100644 --- a/net/rxrpc/conn_client.c +++ b/net/rxrpc/conn_client.c @@ -292,6 +292,12 @@ static int rxrpc_get_client_conn(struct rxrpc_call *call, if (!cp->peer) goto error; + call->cong_cwnd = cp->peer->cong_cwnd; + if (call->cong_cwnd >= call->cong_ssthresh) + call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE; + else + call->cong_mode = RXRPC_CALL_SLOW_START; + /* If the connection is not meant to be exclusive, search the available * connections to see if the connection we want to use already exists. */ diff --git a/net/rxrpc/conn_object.c b/net/rxrpc/conn_object.c index 5bb255107427..929b50d5afe8 100644 --- a/net/rxrpc/conn_object.c +++ b/net/rxrpc/conn_object.c @@ -193,6 +193,8 @@ void rxrpc_disconnect_call(struct rxrpc_call *call) { struct rxrpc_connection *conn = call->conn; + call->peer->cong_cwnd = call->cong_cwnd; + spin_lock_bh(&conn->params.peer->lock); hlist_del_init(&call->error_link); spin_unlock_bh(&conn->params.peer->lock); diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c index cfed3b27adf0..5787f97f5330 100644 --- a/net/rxrpc/peer_object.c +++ b/net/rxrpc/peer_object.c @@ -228,6 +228,13 @@ struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp) seqlock_init(&peer->service_conn_lock); spin_lock_init(&peer->lock); peer->debug_id = atomic_inc_return(&rxrpc_debug_id); + + if (RXRPC_TX_SMSS > 2190) + peer->cong_cwnd = 2; + else if (RXRPC_TX_SMSS > 1095) + peer->cong_cwnd = 3; + else + peer->cong_cwnd = 4; } _leave(" = %p", peer); -- 2.20.1