Commit fb4d3d1d authored by Yuchung Cheng's avatar Yuchung Cheng Committed by David S. Miller
Browse files

tcp: move tcp_update_cwnd_in_recovery



To prepare replacing rate halving with PRR algorithm in CWR state.
Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 09484d1f
......@@ -2700,6 +2700,38 @@ static bool tcp_try_undo_loss(struct sock *sk)
return false;
}
/* This function implements the PRR algorithm, specifcally the PRR-SSRB
* (proportional rate reduction with slow start reduction bound) as described in
* http://www.ietf.org/id/draft-mathis-tcpm-proportional-rate-reduction-01.txt.
* It computes the number of packets to send (sndcnt) based on packets newly
* delivered:
* 1) If the packets in flight is larger than ssthresh, PRR spreads the
* cwnd reductions across a full RTT.
* 2) If packets in flight is lower than ssthresh (such as due to excess
* losses and/or application stalls), do not perform any further cwnd
* reductions, but instead slow start up to ssthresh.
*/
static void tcp_update_cwnd_in_recovery(struct sock *sk, int newly_acked_sacked,
int fast_rexmit, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
int sndcnt = 0;
int delta = tp->snd_ssthresh - tcp_packets_in_flight(tp);
if (tcp_packets_in_flight(tp) > tp->snd_ssthresh) {
u64 dividend = (u64)tp->snd_ssthresh * tp->prr_delivered +
tp->prior_cwnd - 1;
sndcnt = div_u64(dividend, tp->prior_cwnd) - tp->prr_out;
} else {
sndcnt = min_t(int, delta,
max_t(int, tp->prr_delivered - tp->prr_out,
newly_acked_sacked) + 1);
}
sndcnt = max(sndcnt, (fast_rexmit ? 1 : 0));
tp->snd_cwnd = tcp_packets_in_flight(tp) + sndcnt;
}
static inline void tcp_complete_cwr(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
......@@ -2854,38 +2886,6 @@ void tcp_simple_retransmit(struct sock *sk)
}
EXPORT_SYMBOL(tcp_simple_retransmit);
/* This function implements the PRR algorithm, specifcally the PRR-SSRB
* (proportional rate reduction with slow start reduction bound) as described in
* http://www.ietf.org/id/draft-mathis-tcpm-proportional-rate-reduction-01.txt.
* It computes the number of packets to send (sndcnt) based on packets newly
* delivered:
* 1) If the packets in flight is larger than ssthresh, PRR spreads the
* cwnd reductions across a full RTT.
* 2) If packets in flight is lower than ssthresh (such as due to excess
* losses and/or application stalls), do not perform any further cwnd
* reductions, but instead slow start up to ssthresh.
*/
static void tcp_update_cwnd_in_recovery(struct sock *sk, int newly_acked_sacked,
int fast_rexmit, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
int sndcnt = 0;
int delta = tp->snd_ssthresh - tcp_packets_in_flight(tp);
if (tcp_packets_in_flight(tp) > tp->snd_ssthresh) {
u64 dividend = (u64)tp->snd_ssthresh * tp->prr_delivered +
tp->prior_cwnd - 1;
sndcnt = div_u64(dividend, tp->prior_cwnd) - tp->prr_out;
} else {
sndcnt = min_t(int, delta,
max_t(int, tp->prr_delivered - tp->prr_out,
newly_acked_sacked) + 1);
}
sndcnt = max(sndcnt, (fast_rexmit ? 1 : 0));
tp->snd_cwnd = tcp_packets_in_flight(tp) + sndcnt;
}
static void tcp_enter_recovery(struct sock *sk, bool ece_ack)
{
struct tcp_sock *tp = tcp_sk(sk);
......
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