From f50168dfeddc5bb4133e1a416ee9548986ec8b4c Mon Sep 17 00:00:00 2001
From: Tatsuhiro Tsujikawa <tatsuhiro.t@gmail.com>
Date: Fri, 22 May 2020 20:35:05 +0900
Subject: [PATCH] Don't increase cwnd if it exceeds target cwnd
---
lib/ngtcp2_cc.c | 19 +++++++++++++++++--
lib/ngtcp2_cc.h | 5 +++++
lib/ngtcp2_conn.c | 10 +++-------
lib/ngtcp2_rtb.c | 11 ++++++-----
4 files changed, 31 insertions(+), 14 deletions(-)
diff --git a/lib/ngtcp2_cc.c b/lib/ngtcp2_cc.c
index 072cbed0..82fcf70c 100644
--- a/lib/ngtcp2_cc.c
+++ b/lib/ngtcp2_cc.c
@@ -31,6 +31,12 @@
#include "ngtcp2_mem.h"
#include "ngtcp2_rcvry.h"
+uint64_t ngtcp2_cc_compute_initcwnd(size_t max_packet_size) {
+ uint64_t n = 2 * max_packet_size;
+ n = ngtcp2_max(n, 14720);
+ return ngtcp2_min(10 * max_packet_size, n);
+}
+
ngtcp2_cc_pkt *ngtcp2_cc_pkt_init(ngtcp2_cc_pkt *pkt, int64_t pkt_num,
size_t pktlen, ngtcp2_tstamp ts_sent) {
pkt->pkt_num = pkt_num;
@@ -95,6 +101,10 @@ void ngtcp2_cc_reno_cc_on_pkt_acked(ngtcp2_cc *ccx, ngtcp2_conn_stat *cstat,
return;
}
+ if (cc->target_cwnd && cc->target_cwnd < cstat->cwnd) {
+ return;
+ }
+
if (cstat->cwnd < cstat->ssthresh) {
cstat->cwnd += pkt->pktlen;
ngtcp2_log_info(cc->ccb.log, NGTCP2_LOG_EVENT_RCV,
@@ -150,7 +160,8 @@ void ngtcp2_cc_reno_cc_on_ack_recv(ngtcp2_cc *ccx, ngtcp2_conn_stat *cstat,
if (cstat->min_rtt != UINT64_MAX && cc->max_delivery_rate_sec) {
target_cwnd =
cc->max_delivery_rate_sec * cstat->min_rtt * 289 / NGTCP2_SECONDS / 100;
- min_cwnd = 2 * cstat->max_packet_size;
+
+ min_cwnd = ngtcp2_cc_compute_initcwnd(cstat->max_packet_size) * 289 / 100;
cc->target_cwnd = ngtcp2_max(min_cwnd, target_cwnd);
ngtcp2_log_info(cc->ccb.log, NGTCP2_LOG_EVENT_RCV,
@@ -233,6 +244,10 @@ void ngtcp2_cc_cubic_cc_on_pkt_acked(ngtcp2_cc *ccx, ngtcp2_conn_stat *cstat,
return;
}
+ if (cc->target_cwnd && cc->target_cwnd < cstat->cwnd) {
+ return;
+ }
+
if (cstat->cwnd < cstat->ssthresh) {
/* slow-start */
cstat->cwnd += pkt->pktlen;
@@ -362,7 +377,7 @@ void ngtcp2_cc_cubic_cc_on_ack_recv(ngtcp2_cc *ccx, ngtcp2_conn_stat *cstat,
target_cwnd =
cc->max_delivery_rate_sec * cstat->min_rtt * 289 / NGTCP2_SECONDS / 100;
- min_cwnd = 2 * cstat->max_packet_size;
+ min_cwnd = ngtcp2_cc_compute_initcwnd(cstat->max_packet_size) * 289 / 100;
cc->target_cwnd = ngtcp2_max(min_cwnd, target_cwnd);
ngtcp2_log_info(cc->ccb.log, NGTCP2_LOG_EVENT_RCV,
diff --git a/lib/ngtcp2_cc.h b/lib/ngtcp2_cc.h
index c606d854..9fbeaac3 100644
--- a/lib/ngtcp2_cc.h
+++ b/lib/ngtcp2_cc.h
@@ -37,6 +37,11 @@
struct ngtcp2_log;
typedef struct ngtcp2_log ngtcp2_log;
+/*
+ * ngtcp2_cc_compute_initcwnd computes initial cwnd.
+ */
+uint64_t ngtcp2_cc_compute_initcwnd(size_t max_packet_size);
+
ngtcp2_cc_pkt *ngtcp2_cc_pkt_init(ngtcp2_cc_pkt *pkt, int64_t pkt_num,
size_t pktlen, ngtcp2_tstamp ts_sent);
diff --git a/lib/ngtcp2_conn.c b/lib/ngtcp2_conn.c
index 32deb41c..4c51c7af 100644
--- a/lib/ngtcp2_conn.c
+++ b/lib/ngtcp2_conn.c
@@ -514,8 +514,6 @@ static int ts_retired_less(const ngtcp2_pq_entry *lhs,
}
static void conn_reset_conn_stat(ngtcp2_conn *conn, ngtcp2_conn_stat *cstat) {
- uint64_t cwnd, min_cwnd;
-
memset(cstat, 0, sizeof(*cstat));
cstat->smoothed_rtt = NGTCP2_DEFAULT_INITIAL_RTT;
cstat->rttvar = NGTCP2_DEFAULT_INITIAL_RTT / 2;
@@ -524,9 +522,7 @@ static void conn_reset_conn_stat(ngtcp2_conn *conn, ngtcp2_conn_stat *cstat) {
memset(cstat->last_tx_pkt_ts, 0xff, sizeof(cstat->last_tx_pkt_ts));
memset(cstat->loss_time, 0xff, sizeof(cstat->loss_time));
cstat->max_packet_size = conn->local.settings.max_packet_size;
- min_cwnd = 2 * cstat->max_packet_size;
- cwnd = ngtcp2_max(min_cwnd, 14720);
- cstat->cwnd = ngtcp2_min(10 * cstat->max_packet_size, cwnd);
+ cstat->cwnd = ngtcp2_cc_compute_initcwnd(cstat->max_packet_size);
cstat->ssthresh = UINT64_MAX;
}
@@ -1228,7 +1224,7 @@ static uint64_t conn_cwnd_is_zero(ngtcp2_conn *conn) {
uint64_t bytes_in_flight = conn->cstat.bytes_in_flight;
uint64_t cwnd =
conn->pv && (conn->pv->flags & NGTCP2_PV_FLAG_FALLBACK_ON_FAILURE)
- ? /* min_cwnd = */ 2 * conn->cstat.max_packet_size
+ ? ngtcp2_cc_compute_initcwnd(conn->cstat.max_packet_size)
: conn->cstat.cwnd;
return bytes_in_flight >= cwnd;
@@ -8888,7 +8884,7 @@ void ngtcp2_conn_update_rtt(ngtcp2_conn *conn, ngtcp2_duration rtt,
ngtcp2_duration ack_delay) {
ngtcp2_conn_stat *cstat = &conn->cstat;
- rtt = ngtcp2_max(rtt, NGTCP2_NANOSECONDS);
+ rtt = ngtcp2_max(rtt, NGTCP2_GRANULARITY);
cstat->latest_rtt = rtt;
diff --git a/lib/ngtcp2_rtb.c b/lib/ngtcp2_rtb.c
index b2ce59a9..e1c08d60 100644
--- a/lib/ngtcp2_rtb.c
+++ b/lib/ngtcp2_rtb.c
@@ -446,6 +446,9 @@ ngtcp2_ssize ngtcp2_rtb_recv_ack(ngtcp2_rtb *rtb, const ngtcp2_ack *fr,
ngtcp2_conn_update_rtt(conn, pkt_ts - largest_pkt_sent_ts,
fr->ack_delay_unscaled);
}
+
+ ngtcp2_rst_on_ack_recv(rtb->rst, cstat);
+ cc->on_ack_recv(cc, cstat, ts);
rtb_on_pkt_acked(rtb, ent, cstat, ts);
/* At this point, it is invalided because rtb->ents might be
modified. */
@@ -483,6 +486,9 @@ ngtcp2_ssize ngtcp2_rtb_recv_ack(ngtcp2_rtb *rtb, const ngtcp2_ack *fr,
ngtcp2_conn_update_rtt(conn, pkt_ts - largest_pkt_sent_ts,
fr->ack_delay_unscaled);
}
+
+ ngtcp2_rst_on_ack_recv(rtb->rst, cstat);
+ cc->on_ack_recv(cc, cstat, ts);
rtb_on_pkt_acked(rtb, ent, cstat, ts);
}
rtb_remove(rtb, &it, ent, cstat);
@@ -492,11 +498,6 @@ ngtcp2_ssize ngtcp2_rtb_recv_ack(ngtcp2_rtb *rtb, const ngtcp2_ack *fr,
++i;
}
- if (conn) {
- ngtcp2_rst_on_ack_recv(rtb->rst, cstat);
- cc->on_ack_recv(cc, cstat, ts);
- }
-
return num_acked;
}
--
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