* http://www.hamilton.ie/net/htcp3.pdf
*/
-#include <linux/config.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <net/tcp.h>
-#define ALPHA_BASE (1<<7) /* 1.0 with shift << 7 */
-#define BETA_MIN (1<<6) /* 0.5 with shift << 7 */
+#define ALPHA_BASE (1<<7) /* 1.0 with shift << 7 */
+#define BETA_MIN (1<<6) /* 0.5 with shift << 7 */
#define BETA_MAX 102 /* 0.8 with shift << 7 */
-static int use_rtt_scaling = 1;
+static int use_rtt_scaling __read_mostly = 1;
module_param(use_rtt_scaling, int, 0644);
MODULE_PARM_DESC(use_rtt_scaling, "turn on/off RTT scaling");
-static int use_bandwidth_switch = 1;
+static int use_bandwidth_switch __read_mostly = 1;
module_param(use_bandwidth_switch, int, 0644);
MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher");
struct htcp {
- u16 alpha; /* Fixed point arith, << 7 */
+ u32 alpha; /* Fixed point arith, << 7 */
u8 beta; /* Fixed point arith, << 7 */
- u8 modeswitch; /* Delay modeswitch until we had at least one congestion event */
- u8 ccount; /* Number of RTTs since last congestion event */
- u8 undo_ccount;
- u16 packetcount;
+ u8 modeswitch; /* Delay modeswitch
+ until we had at least one congestion event */
+ u16 pkts_acked;
+ u32 packetcount;
u32 minRTT;
u32 maxRTT;
- u32 snd_cwnd_cnt2;
+ u32 last_cong; /* Time since last congestion event end */
+ u32 undo_last_cong;
u32 undo_maxRTT;
u32 undo_old_maxB;
u32 lasttime;
};
+static inline u32 htcp_cong_time(const struct htcp *ca)
+{
+ return jiffies - ca->last_cong;
+}
+
+static inline u32 htcp_ccount(const struct htcp *ca)
+{
+ return htcp_cong_time(ca) / ca->minRTT;
+}
+
static inline void htcp_reset(struct htcp *ca)
{
- ca->undo_ccount = ca->ccount;
+ ca->undo_last_cong = ca->last_cong;
ca->undo_maxRTT = ca->maxRTT;
ca->undo_old_maxB = ca->old_maxB;
- ca->ccount = 0;
- ca->snd_cwnd_cnt2 = 0;
+ ca->last_cong = jiffies;
}
-static u32 htcp_cwnd_undo(struct tcp_sock *tp)
+static u32 htcp_cwnd_undo(struct sock *sk)
{
- struct htcp *ca = tcp_ca(tp);
- 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);
+ const struct tcp_sock *tp = tcp_sk(sk);
+ struct htcp *ca = inet_csk_ca(sk);
+
+ if (ca->undo_last_cong) {
+ ca->last_cong = ca->undo_last_cong;
+ ca->maxRTT = ca->undo_maxRTT;
+ ca->old_maxB = ca->undo_old_maxB;
+ ca->undo_last_cong = 0;
+ }
+
+ return max(tp->snd_cwnd, (tp->snd_ssthresh << 7) / ca->beta);
}
-static inline void measure_rtt(struct tcp_sock *tp)
+static inline void measure_rtt(struct sock *sk, u32 srtt)
{
- struct htcp *ca = tcp_ca(tp);
- u32 srtt = tp->srtt>>3;
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+ struct htcp *ca = inet_csk_ca(sk);
/* keep track of minimum RTT seen so far, minRTT is zero at first */
if (ca->minRTT > srtt || !ca->minRTT)
ca->minRTT = srtt;
/* max RTT */
- if (tp->ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && ca->ccount > 3) {
+ if (icsk->icsk_ca_state == TCP_CA_Open) {
if (ca->maxRTT < ca->minRTT)
ca->maxRTT = ca->minRTT;
- if (ca->maxRTT < srtt && srtt <= ca->maxRTT+HZ/50)
+ if (ca->maxRTT < srtt
+ && srtt <= ca->maxRTT + msecs_to_jiffies(20))
ca->maxRTT = srtt;
}
}
-static void measure_achieved_throughput(struct tcp_sock *tp, u32 pkts_acked)
+static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked, s32 rtt)
{
- struct htcp *ca = tcp_ca(tp);
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+ const struct tcp_sock *tp = tcp_sk(sk);
+ 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 (rtt > 0)
+ measure_rtt(sk, usecs_to_jiffies(rtt));
+
+ if (!use_bandwidth_switch)
+ return;
+
/* achieved throughput calculations */
- if (tp->ca_state != TCP_CA_Open && tp->ca_state != TCP_CA_Disorder) {
+ if (!((1 << icsk->icsk_ca_state) & (TCPF_CA_Open | TCPF_CA_Disorder))) {
ca->packetcount = 0;
ca->lasttime = now;
return;
ca->packetcount += pkts_acked;
- if (ca->packetcount >= tp->snd_cwnd - (ca->alpha>>7? : 1)
- && now - ca->lasttime >= ca->minRTT
- && ca->minRTT > 0) {
- __u32 cur_Bi = ca->packetcount*HZ/(now - ca->lasttime);
- if (ca->ccount <= 3) {
+ if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1)
+ && now - ca->lasttime >= ca->minRTT
+ && ca->minRTT > 0) {
+ __u32 cur_Bi = ca->packetcount * HZ / (now - ca->lasttime);
+
+ if (htcp_ccount(ca) <= 3) {
/* just after backoff */
ca->minB = ca->maxB = ca->Bi = cur_Bi;
} else {
- ca->Bi = (3*ca->Bi + cur_Bi)/4;
+ ca->Bi = (3 * ca->Bi + cur_Bi) / 4;
if (ca->Bi > ca->maxB)
ca->maxB = ca->Bi;
if (ca->minB > ca->maxB)
u32 old_maxB = ca->old_maxB;
ca->old_maxB = ca->maxB;
- if (!between(5*maxB, 4*old_maxB, 6*old_maxB)) {
+ if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) {
ca->beta = BETA_MIN;
ca->modeswitch = 0;
return;
}
}
- if (ca->modeswitch && minRTT > max(HZ/100, 1) && maxRTT) {
- ca->beta = (minRTT<<7)/maxRTT;
+ if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) {
+ ca->beta = (minRTT << 7) / maxRTT;
if (ca->beta < BETA_MIN)
ca->beta = BETA_MIN;
else if (ca->beta > BETA_MAX)
{
u32 minRTT = ca->minRTT;
u32 factor = 1;
- u32 diff = ca->ccount * minRTT; /* time since last backoff */
+ u32 diff = htcp_cong_time(ca);
if (diff > HZ) {
diff -= HZ;
- factor = 1+ ( 10*diff + ((diff/2)*(diff/2)/HZ) )/HZ;
+ factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / HZ)) / HZ;
}
if (use_rtt_scaling && minRTT) {
- u32 scale = (HZ<<3)/(10*minRTT);
- scale = min(max(scale, 1U<<2), 10U<<3); /* clamping ratio to interval [0.5,10]<<3 */
- factor = (factor<<3)/scale;
+ u32 scale = (HZ << 3) / (10 * minRTT);
+
+ /* clamping ratio to interval [0.5,10]<<3 */
+ scale = min(max(scale, 1U << 2), 10U << 3);
+ factor = (factor << 3) / scale;
if (!factor)
factor = 1;
}
- ca->alpha = 2*factor*((1<<7)-ca->beta);
+ ca->alpha = 2 * factor * ((1 << 7) - ca->beta);
if (!ca->alpha)
ca->alpha = ALPHA_BASE;
}
-/* After we have the rtt data to calculate beta, we'd still prefer to wait one
+/*
+ * After we have the rtt data to calculate beta, we'd still prefer to wait one
* rtt before we adjust our beta to ensure we are working from a consistent
* data.
*
* that point do we really have a real sense of maxRTT (the queues en route
* were getting just too full now).
*/
-static void htcp_param_update(struct tcp_sock *tp)
+static void htcp_param_update(struct sock *sk)
{
- struct htcp *ca = tcp_ca(tp);
+ struct htcp *ca = inet_csk_ca(sk);
u32 minRTT = ca->minRTT;
u32 maxRTT = ca->maxRTT;
htcp_beta_update(ca, minRTT, maxRTT);
htcp_alpha_update(ca);
- /* add slowly fading memory for maxRTT to accommodate routing changes etc */
+ /* add slowly fading memory for maxRTT to accommodate routing changes */
if (minRTT > 0 && maxRTT > minRTT)
- ca->maxRTT = minRTT + ((maxRTT-minRTT)*95)/100;
+ ca->maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100;
}
-static u32 htcp_recalc_ssthresh(struct tcp_sock *tp)
+static u32 htcp_recalc_ssthresh(struct sock *sk)
{
- struct htcp *ca = tcp_ca(tp);
- htcp_param_update(tp);
+ const struct tcp_sock *tp = tcp_sk(sk);
+ const struct htcp *ca = inet_csk_ca(sk);
+
+ htcp_param_update(sk);
return max((tp->snd_cwnd * ca->beta) >> 7, 2U);
}
-static void htcp_cong_avoid(struct tcp_sock *tp, u32 ack, u32 rtt,
- u32 in_flight, int data_acked)
+static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 in_flight)
{
- struct htcp *ca = tcp_ca(tp);
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct htcp *ca = inet_csk_ca(sk);
- if (in_flight < tp->snd_cwnd)
+ if (!tcp_is_cwnd_limited(sk, in_flight))
return;
- if (tp->snd_cwnd <= tp->snd_ssthresh) {
- /* In "safe" area, increase. */
- if (tp->snd_cwnd < tp->snd_cwnd_clamp)
- tp->snd_cwnd++;
- } else {
- measure_rtt(tp);
-
- /* 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.
+ if (tp->snd_cwnd <= tp->snd_ssthresh)
+ tcp_slow_start(tp);
+ else {
+ /* 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;
- ca->ccount++;
- }
- }
-}
+ htcp_alpha_update(ca);
+ } else
+ tp->snd_cwnd_cnt += ca->pkts_acked;
-/* Lower bound on congestion window. */
-static u32 htcp_min_cwnd(struct tcp_sock *tp)
-{
- return tp->snd_ssthresh;
+ ca->pkts_acked = 1;
+ }
}
-
-static void htcp_init(struct tcp_sock *tp)
+static void htcp_init(struct sock *sk)
{
- struct htcp *ca = tcp_ca(tp);
+ 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 tcp_sock *tp, u8 new_state)
+static void htcp_state(struct sock *sk, u8 new_state)
{
switch (new_state) {
+ case TCP_CA_Open:
+ {
+ struct htcp *ca = inet_csk_ca(sk);
+ if (ca->undo_last_cong) {
+ ca->last_cong = jiffies;
+ ca->undo_last_cong = 0;
+ }
+ }
+ break;
case TCP_CA_CWR:
case TCP_CA_Recovery:
case TCP_CA_Loss:
- htcp_reset(tcp_ca(tp));
+ htcp_reset(inet_csk_ca(sk));
break;
}
}
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,
static int __init htcp_register(void)
{
- BUG_ON(sizeof(struct htcp) > TCP_CA_PRIV_SIZE);
+ BUILD_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);
}