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/*
* Copyright (c) 2017 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <vnet/tcp/tcp.h>
void
newreno_congestion (tcp_connection_t * tc)
{
tc->ssthresh = clib_max (tcp_flight_size (tc) / 2, 2 * tc->snd_mss);
}
void
newreno_recovered (tcp_connection_t * tc)
{
tc->cwnd = tc->ssthresh;
}
void
newreno_rcv_ack (tcp_connection_t * tc)
{
if (tcp_in_slowstart (tc))
{
tc->cwnd += clib_min (tc->snd_mss, tc->bytes_acked);
}
else
{
/* Round up to 1 if needed */
tc->cwnd += clib_max ((tc->snd_mss * tc->snd_mss) / tc->cwnd, 1);
}
}
void
newreno_rcv_cong_ack (tcp_connection_t * tc, tcp_cc_ack_t ack_type)
{
if (ack_type == TCP_CC_DUPACK)
{
if (!tcp_opts_sack_permitted (tc))
tc->cwnd += tc->snd_mss;
}
else if (ack_type == TCP_CC_PARTIALACK)
{
/* RFC 6582 Sec. 3.2 */
if (!tcp_opts_sack_permitted (&tc->rcv_opts))
{
/* Deflate the congestion window by the amount of new data
* acknowledged by the Cumulative Acknowledgment field.
* If the partial ACK acknowledges at least one SMSS of new data,
* then add back SMSS bytes to the congestion window. This
* artificially inflates the congestion window in order to reflect
* the additional segment that has left the network. This "partial
* window deflation" attempts to ensure that, when fast recovery
* eventually ends, approximately ssthresh amount of data will be
* outstanding in the network.*/
tc->cwnd = (tc->cwnd > tc->bytes_acked + tc->snd_mss) ?
tc->cwnd - tc->bytes_acked : tc->snd_mss;
if (tc->bytes_acked > tc->snd_mss)
tc->cwnd += tc->snd_mss;
}
}
}
void
newreno_conn_init (tcp_connection_t * tc)
{
tc->ssthresh = tc->snd_wnd;
tc->cwnd = tcp_initial_cwnd (tc);
}
const static tcp_cc_algorithm_t tcp_newreno = {
.congestion = newreno_congestion,
.recovered = newreno_recovered,
.rcv_ack = newreno_rcv_ack,
.rcv_cong_ack = newreno_rcv_cong_ack,
.init = newreno_conn_init
};
clib_error_t *
newreno_init (vlib_main_t * vm)
{
clib_error_t *error = 0;
tcp_cc_algo_register (TCP_CC_NEWRENO, &tcp_newreno);
return error;
}
VLIB_INIT_FUNCTION (newreno_init);
/*
* fd.io coding-style-patch-verification: ON
*
* Local Variables:
* eval: (c-set-style "gnu")
* End:
*/
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