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 <dhowe...@redhat.com>
---
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);
