Commit f7aec129 authored by David Howells's avatar David Howells Committed by David S. Miller

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: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0430a260
......@@ -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 */
};
/*
......
......@@ -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;
}
......
......@@ -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_ssthresh = RXRPC_RXTX_BUFF_SIZE - 1;
return call;
......
......@@ -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.
*/
......
......@@ -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);
......
......@@ -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);
......
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