* http://www.hamilton.ie/net/htcp3.pdf
*/
+#include <linux/config.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <net/tcp.h>
u16 alpha; /* Fixed point arith, << 7 */
u8 beta; /* Fixed point arith, << 7 */
u8 modeswitch; /* Delay modeswitch until we had at least one congestion event */
- u32 last_cong; /* Time since last congestion event end */
- u32 undo_last_cong;
- u16 pkts_acked;
- u32 packetcount;
+ u8 ccount; /* Number of RTTs since last congestion event */
+ u8 undo_ccount;
+ u16 packetcount;
u32 minRTT;
u32 maxRTT;
+ u32 snd_cwnd_cnt2;
u32 undo_maxRTT;
u32 undo_old_maxB;
u32 lasttime;
};
-static inline u32 htcp_cong_time(struct htcp *ca)
-{
- return jiffies - ca->last_cong;
-}
-
-static inline u32 htcp_ccount(struct htcp *ca)
-{
- return htcp_cong_time(ca)/ca->minRTT;
-}
-
static inline void htcp_reset(struct htcp *ca)
{
- ca->undo_last_cong = ca->last_cong;
+ ca->undo_ccount = ca->ccount;
ca->undo_maxRTT = ca->maxRTT;
ca->undo_old_maxB = ca->old_maxB;
- ca->last_cong = jiffies;
+ ca->ccount = 0;
+ ca->snd_cwnd_cnt2 = 0;
}
static u32 htcp_cwnd_undo(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
struct htcp *ca = inet_csk_ca(sk);
- ca->last_cong = ca->undo_last_cong;
+ ca->ccount = ca->undo_ccount;
ca->maxRTT = ca->undo_maxRTT;
ca->old_maxB = ca->undo_old_maxB;
return max(tp->snd_cwnd, (tp->snd_ssthresh<<7)/ca->beta);
ca->minRTT = srtt;
/* max RTT */
- if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && htcp_ccount(ca) > 3) {
+ if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && ca->ccount > 3) {
if (ca->maxRTT < ca->minRTT)
ca->maxRTT = ca->minRTT;
- if (ca->maxRTT < srtt && srtt <= ca->maxRTT+msecs_to_jiffies(20))
+ if (ca->maxRTT < srtt && srtt <= ca->maxRTT+HZ/50)
ca->maxRTT = srtt;
}
}
struct htcp *ca = inet_csk_ca(sk);
u32 now = tcp_time_stamp;
- if (icsk->icsk_ca_state == TCP_CA_Open)
- ca->pkts_acked = pkts_acked;
-
- if (!use_bandwidth_switch)
- return;
-
/* achieved throughput calculations */
if (icsk->icsk_ca_state != TCP_CA_Open &&
icsk->icsk_ca_state != TCP_CA_Disorder) {
&& now - ca->lasttime >= ca->minRTT
&& ca->minRTT > 0) {
__u32 cur_Bi = ca->packetcount*HZ/(now - ca->lasttime);
- if (htcp_ccount(ca) <= 3) {
+ if (ca->ccount <= 3) {
/* just after backoff */
ca->minB = ca->maxB = ca->Bi = cur_Bi;
} else {
}
}
- if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) {
+ if (ca->modeswitch && minRTT > max(HZ/100, 1) && maxRTT) {
ca->beta = (minRTT<<7)/maxRTT;
if (ca->beta < BETA_MIN)
ca->beta = BETA_MIN;
{
u32 minRTT = ca->minRTT;
u32 factor = 1;
- u32 diff = htcp_cong_time(ca);
+ u32 diff = ca->ccount * minRTT; /* time since last backoff */
if (diff > HZ) {
diff -= HZ;
measure_rtt(sk);
+ /* keep track of number of round-trip times since last backoff event */
+ if (ca->snd_cwnd_cnt2++ > tp->snd_cwnd) {
+ ca->ccount++;
+ ca->snd_cwnd_cnt2 = 0;
+ htcp_alpha_update(ca);
+ }
+
/* In dangerous area, increase slowly.
* In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
*/
- if ((tp->snd_cwnd_cnt * ca->alpha)>>7 >= tp->snd_cwnd) {
+ if ((tp->snd_cwnd_cnt++ * ca->alpha)>>7 >= tp->snd_cwnd) {
if (tp->snd_cwnd < tp->snd_cwnd_clamp)
tp->snd_cwnd++;
tp->snd_cwnd_cnt = 0;
- htcp_alpha_update(ca);
- } else
- tp->snd_cwnd_cnt += ca->pkts_acked;
-
- ca->pkts_acked = 1;
+ }
}
}
+/* Lower bound on congestion window. */
+static u32 htcp_min_cwnd(struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ return tp->snd_ssthresh;
+}
+
+
static void htcp_init(struct sock *sk)
{
struct htcp *ca = inet_csk_ca(sk);
memset(ca, 0, sizeof(struct htcp));
ca->alpha = ALPHA_BASE;
ca->beta = BETA_MIN;
- ca->pkts_acked = 1;
- ca->last_cong = jiffies;
}
static void htcp_state(struct sock *sk, u8 new_state)
{
switch (new_state) {
- case TCP_CA_Open:
- {
- struct htcp *ca = inet_csk_ca(sk);
- ca->last_cong = jiffies;
- }
- break;
case TCP_CA_CWR:
case TCP_CA_Recovery:
case TCP_CA_Loss:
static struct tcp_congestion_ops htcp = {
.init = htcp_init,
.ssthresh = htcp_recalc_ssthresh,
+ .min_cwnd = htcp_min_cwnd,
.cong_avoid = htcp_cong_avoid,
.set_state = htcp_state,
.undo_cwnd = htcp_cwnd_undo,
{
BUG_ON(sizeof(struct htcp) > ICSK_CA_PRIV_SIZE);
BUILD_BUG_ON(BETA_MIN >= BETA_MAX);
+ if (!use_bandwidth_switch)
+ htcp.pkts_acked = NULL;
return tcp_register_congestion_control(&htcp);
}