static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack,
u32 seq_rtt, u32 in_flight, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
struct yeah *yeah = (struct yeah*) inet_csk_ca(sk);
if (!tcp_is_cwnd_limited(sk, in_flight))
return;
if (tp->snd_cwnd <= tp->snd_ssthresh)
tcp_slow_start(tp);
else if (!yeah->doing_reno_now) {
/* Scalable */
tp->snd_cwnd_cnt+=yeah->pkts_acked;
if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){
if (tp->snd_cwnd < tp->snd_cwnd_clamp)
tp->snd_cwnd++;
tp->snd_cwnd_cnt = 0;
}
yeah->pkts_acked = 1;
} else {
/* Reno */
if (tp->snd_cwnd_cnt < tp->snd_cwnd)
tp->snd_cwnd_cnt++;
if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
tp->snd_cwnd++;
tp->snd_cwnd_cnt = 0;
}
}
/* The key players are v_vegas.beg_snd_una and v_beg_snd_nxt.
*
* These are so named because they represent the approximate values
* of snd_una and snd_nxt at the beginning of the current RTT. More
* precisely, they represent the amount of data sent during the RTT.
* At the end of the RTT, when we receive an ACK for v_beg_snd_nxt,
* we will calculate that (v_beg_snd_nxt - v_vegas.beg_snd_una) outstanding
* bytes of data have been ACKed during the course of the RTT, giving
* an "actual" rate of:
*
* (v_beg_snd_nxt - v_vegas.beg_snd_una) / (rtt duration)
*
* Unfortunately, v_vegas.beg_snd_una is not exactly equal to snd_una,
* because delayed ACKs can cover more than one segment, so they
* don't line up yeahly with the boundaries of RTTs.
*
* Another unfortunate fact of life is that delayed ACKs delay the
* advance of the left edge of our send window, so that the number
* of bytes we send in an RTT is often less than our cwnd will allow.
* So we keep track of our cwnd separately, in v_beg_snd_cwnd.
*/
if (after(ack, yeah->vegas.beg_snd_nxt)) {
/* We do the Vegas calculations only if we got enough RTT
* samples that we can be reasonably sure that we got
* at least one RTT sample that wasn't from a delayed ACK.
* If we only had 2 samples total,
* then that means we're getting only 1 ACK per RTT, which
* means they're almost certainly delayed ACKs.
* If we have 3 samples, we should be OK.
*/
if (yeah->vegas.cntRTT > 2) {
u32 rtt, queue;
u64 bw;
/* We have enough RTT samples, so, using the Vegas
* algorithm, we determine if we should increase or
* decrease cwnd, and by how much.
*/
/* Pluck out the RTT we are using for the Vegas
* calculations. This is the min RTT seen during the
* last RTT. Taking the min filters out the effects
* of delayed ACKs, at the cost of noticing congestion
* a bit later.
*/
rtt = yeah->vegas.minRTT;
/* Compute excess number of packets above bandwidth
* Avoid doing full 64 bit divide.
*/
bw = tp->snd_cwnd;
bw *= rtt - yeah->vegas.baseRTT;
do_div(bw, rtt);
queue = bw;
if (queue > TCP_YEAH_ALPHA ||
rtt - yeah->vegas.baseRTT > (yeah->vegas.baseRTT / TCP_YEAH_PHY)) {
if (queue > TCP_YEAH_ALPHA
&& tp->snd_cwnd > yeah->reno_count) {
u32 reduction = min(queue / TCP_YEAH_GAMMA ,
tp->snd_cwnd >> TCP_YEAH_EPSILON);
tp->snd_cwnd -= reduction;
tp->snd_cwnd = max(tp->snd_cwnd,
yeah->reno_count);
tp->snd_ssthresh = tp->snd_cwnd;
}
if (yeah->reno_count <= 2)
yeah->reno_count = max(tp->snd_cwnd>>1, 2U);
else
yeah->reno_count++;
yeah->doing_reno_now = min(yeah->doing_reno_now + 1,
0xffffffU);
} else {
static void tcp_veno_cong_avoid(struct sock *sk, u32 ack,
u32 seq_rtt, u32 in_flight, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
struct veno *veno = inet_csk_ca(sk);
if (!veno->doing_veno_now)
return tcp_reno_cong_avoid(sk, ack, seq_rtt, in_flight, flag);
/* limited by applications */
if (!tcp_is_cwnd_limited(sk, in_flight))
return;
/* We do the Veno calculations only if we got enough rtt samples */
if (veno->cntrtt <= 2) {
/* We don't have enough rtt samples to do the Veno
* calculation, so we'll behave like Reno.
*/
tcp_reno_cong_avoid(sk, ack, seq_rtt, in_flight, flag);
} else {
u32 rtt, target_cwnd;
/* We have enough rtt samples, so, using the Veno
* algorithm, we determine the state of the network.
*/
rtt = veno->minrtt;
target_cwnd = ((tp->snd_cwnd * veno->basertt)
<< V_PARAM_SHIFT) / rtt;
veno->diff = (tp->snd_cwnd << V_PARAM_SHIFT) - target_cwnd;
if (tp->snd_cwnd <= tp->snd_ssthresh) {
/* Slow start. */
tcp_slow_start(tp);
} else {
/* Congestion avoidance. */
if (veno->diff < (u32)beta) {
/* In the "non-congestive state", increase cwnd
* every rtt.
*/
if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
if (tp->snd_cwnd < tp->snd_cwnd_clamp)
tp->snd_cwnd++;
tp->snd_cwnd_cnt = 0;
} else
tp->snd_cwnd_cnt++;
} else {
/* In the "congestive state", increase cwnd
* every other rtt.
*/
if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
if (veno->inc
&& tp->snd_cwnd <
tp->snd_cwnd_clamp) {
tp->snd_cwnd++;
veno->inc = 0;
} else
veno->inc = 1;
tp->snd_cwnd_cnt = 0;
} else
tp->snd_cwnd_cnt++;
}
}
if (tp->snd_cwnd < 2)
tp->snd_cwnd = 2;
else if (tp->snd_cwnd > tp->snd_cwnd_clamp)
tp->snd_cwnd = tp->snd_cwnd_clamp;
}
/* Wipe the slate clean for the next rtt. */
/* veno->cntrtt = 0; */
veno->minrtt = 0x7fffffff;
}
