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

net/rxrpc/ar-internal.h

+2 −0
Original line number Diff line number Diff line
@@ -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 */

};



/*

net/rxrpc/call_accept.c

+1 −0
Original line number Diff line number Diff line
@@ -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;

}

net/rxrpc/call_object.c

+1 −6
Original line number Diff line number Diff line
@@ -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;

net/rxrpc/conn_client.c

+6 −0
Original line number Diff line number Diff line
@@ -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.

	 */

net/rxrpc/conn_object.c

+2 −0
Original line number Diff line number Diff line
@@ -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);