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rxrpc: Cache the congestion window setting

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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 <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David Howells 2017-06-14 17:56:50 +01:00 committed by David S. Miller
parent 0430a26054
commit f7aec129a3
6 changed files with 19 additions and 6 deletions
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2
net/rxrpc/ar-internal.h
View File

@ -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 */
};
/*

1
net/rxrpc/call_accept.c
View File

@ -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;
}

7
net/rxrpc/call_object.c
View File

@ -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;

6
net/rxrpc/conn_client.c
View File

@ -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.
*/

2
net/rxrpc/conn_object.c
View File

@ -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);

7
net/rxrpc/peer_object.c
View File

@ -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);