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authorBaruch Even <baruch@ev-en.org>2006-03-20 22:23:10 -0800
committerDavid S. Miller <davem@davemloft.net>2006-03-20 22:23:10 -0800
commit50bf3e224a2963c6dd5098f77bd7233222ebfbd2 (patch)
tree6429bcfa043d34db73ef1bdb48243726e33f8132
parent0bc6d90b82775113bbbe371f5d9fcffefa5fa94d (diff)
[TCP] H-TCP: Better time accounting
Instead of estimating the time since the last congestion event, count it directly. Signed-off-by: Baruch Even <baruch@ev-en.org> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_htcp.c44
1 files changed, 26 insertions, 18 deletions
diff --git a/net/ipv4/tcp_htcp.c b/net/ipv4/tcp_htcp.c
index ac19252e34c..1b2ff53f98e 100644
--- a/net/ipv4/tcp_htcp.c
+++ b/net/ipv4/tcp_htcp.c
@@ -27,13 +27,12 @@ struct htcp {
u16 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;
+ u32 last_cong; /* Time since last congestion event end */
+ u32 undo_last_cong;
u16 pkts_acked;
u32 packetcount;
u32 minRTT;
u32 maxRTT;
- u32 snd_cwnd_cnt2;
u32 undo_maxRTT;
u32 undo_old_maxB;
@@ -46,21 +45,30 @@ struct htcp {
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_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 sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
struct htcp *ca = inet_csk_ca(sk);
- ca->ccount = ca->undo_ccount;
+ ca->last_cong = ca->undo_last_cong;
ca->maxRTT = ca->undo_maxRTT;
ca->old_maxB = ca->undo_old_maxB;
return max(tp->snd_cwnd, (tp->snd_ssthresh<<7)/ca->beta);
@@ -78,7 +86,7 @@ static inline void measure_rtt(struct sock *sk)
ca->minRTT = srtt;
/* max RTT */
- if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && ca->ccount > 3) {
+ if (icsk->icsk_ca_state == TCP_CA_Open && tp->snd_ssthresh < 0xFFFF && htcp_ccount(ca) > 3) {
if (ca->maxRTT < ca->minRTT)
ca->maxRTT = ca->minRTT;
if (ca->maxRTT < srtt && srtt <= ca->maxRTT+msecs_to_jiffies(20))
@@ -113,7 +121,7 @@ static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked)
&& now - ca->lasttime >= ca->minRTT
&& ca->minRTT > 0) {
__u32 cur_Bi = ca->packetcount*HZ/(now - ca->lasttime);
- if (ca->ccount <= 3) {
+ if (htcp_ccount(ca) <= 3) {
/* just after backoff */
ca->minB = ca->maxB = ca->Bi = cur_Bi;
} else {
@@ -158,7 +166,7 @@ static inline void htcp_alpha_update(struct htcp *ca)
{
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;
@@ -223,14 +231,6 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
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 -= tp->snd_cwnd;
- htcp_alpha_update(ca);
- } else
- ca->snd_cwnd_cnt2 += ca->pkts_acked;
-
/* In dangerous area, increase slowly.
* In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd
*/
@@ -238,6 +238,7 @@ static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 rtt,
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;
@@ -261,11 +262,18 @@ static void htcp_init(struct sock *sk)
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: