From: Stephen Hemminger <shemminger@linux-foundation.org>
To: "David S. Miller" <davem@davemloft.net>
Cc: Sangtae Ha <sha2@ncsu.edu>
Cc: Luca De Cicco <ldecicco@gmail.com>
Cc: Gavin McCullagh <gavin.mccullagh@nuim.ie>
Cc: netdev@vger.kernel.org
Subject: [RFC 1/3] TCP: congestion control API pass RTT in microseconds
Date: Thu, 19 Jul 2007 08:41:30 +0100 [thread overview]
Message-ID: <20070719074906.458899848@linux-foundation.org> (raw)
In-Reply-To: 20070719074129.670215301@linux-foundation.org
[-- Attachment #1: tcp-cong-rtt.patch --]
[-- Type: text/plain, Size: 8392 bytes --]
This patch changes the API for the callback that is done after an ACK is
received. It solves a couple of issues:
* Some congestion controls want higher resolution value of RTT
(controlled by TCP_CONG_RTT_SAMPLE flag). These don't really want a ktime, but
all compute a RTT in microseconds.
* Other congestion control could use RTT at jiffies resolution.
To keep API consistent the units should be the same for both cases, just the
resolution should change.
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
--- a/include/net/tcp.h 2007-07-19 08:12:13.000000000 +0100
+++ b/include/net/tcp.h 2007-07-19 08:12:23.000000000 +0100
@@ -661,7 +661,7 @@ struct tcp_congestion_ops {
/* new value of cwnd after loss (optional) */
u32 (*undo_cwnd)(struct sock *sk);
/* hook for packet ack accounting (optional) */
- void (*pkts_acked)(struct sock *sk, u32 num_acked, ktime_t last);
+ void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
/* get info for inet_diag (optional) */
void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
--- a/net/ipv4/tcp_input.c 2007-07-19 08:12:13.000000000 +0100
+++ b/net/ipv4/tcp_input.c 2007-07-19 08:12:23.000000000 +0100
@@ -2490,12 +2490,23 @@ static int tcp_clean_rtx_queue(struct so
tcp_ack_update_rtt(sk, acked, seq_rtt);
tcp_ack_packets_out(sk);
- /* Is the ACK triggering packet unambiguous? */
- if (acked & FLAG_RETRANS_DATA_ACKED)
- last_ackt = net_invalid_timestamp();
+ if (ca_ops->pkts_acked) {
+ s32 rtt_us = -1;
- if (ca_ops->pkts_acked)
- ca_ops->pkts_acked(sk, pkts_acked, last_ackt);
+ /* Is the ACK triggering packet unambiguous? */
+ if (!(acked & FLAG_RETRANS_DATA_ACKED)) {
+ /* High resolution needed and available? */
+ if (ca_ops->flags & TCP_CONG_RTT_STAMP &&
+ !ktime_equal(last_ackt,
+ net_invalid_timestamp()))
+ rtt_us = ktime_us_delta(ktime_get_real(),
+ last_ackt);
+ else if (seq_rtt > 0)
+ rtt_us = jiffies_to_usecs(seq_rtt);
+ }
+
+ ca_ops->pkts_acked(sk, pkts_acked, rtt_us);
+ }
}
#if FASTRETRANS_DEBUG > 0
--- a/net/ipv4/tcp_bic.c 2007-07-17 10:01:51.000000000 +0100
+++ b/net/ipv4/tcp_bic.c 2007-07-19 08:16:35.000000000 +0100
@@ -206,7 +206,7 @@ static void bictcp_state(struct sock *sk
/* Track delayed acknowledgment ratio using sliding window
* ratio = (15*ratio + sample) / 16
*/
-static void bictcp_acked(struct sock *sk, u32 cnt, ktime_t last)
+static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
--- a/net/ipv4/tcp_cubic.c 2007-07-18 22:28:38.000000000 +0100
+++ b/net/ipv4/tcp_cubic.c 2007-07-19 08:21:42.000000000 +0100
@@ -334,7 +334,7 @@ static void bictcp_state(struct sock *sk
/* Track delayed acknowledgment ratio using sliding window
* ratio = (15*ratio + sample) / 16
*/
-static void bictcp_acked(struct sock *sk, u32 cnt, ktime_t last)
+static void bictcp_acked(struct sock *sk, u32 cnt, s32 rtt_us)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
--- a/net/ipv4/tcp_htcp.c 2007-07-18 22:28:38.000000000 +0100
+++ b/net/ipv4/tcp_htcp.c 2007-07-19 08:18:38.000000000 +0100
@@ -98,7 +98,7 @@ static inline void measure_rtt(struct so
}
}
-static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked, ktime_t last)
+static void measure_achieved_throughput(struct sock *sk, u32 pkts_acked, s32 rtt)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
const struct tcp_sock *tp = tcp_sk(sk);
--- a/net/ipv4/tcp_illinois.c 2007-07-19 07:08:45.000000000 +0100
+++ b/net/ipv4/tcp_illinois.c 2007-07-19 08:16:13.000000000 +0100
@@ -83,18 +83,16 @@ static void tcp_illinois_init(struct soc
}
/* Measure RTT for each ack. */
-static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, ktime_t last)
+static void tcp_illinois_acked(struct sock *sk, u32 pkts_acked, s32 rtt)
{
struct illinois *ca = inet_csk_ca(sk);
- u32 rtt;
ca->acked = pkts_acked;
- if (ktime_equal(last, net_invalid_timestamp()))
+ /* dup ack, no rtt sample */
+ if (rtt < 0)
return;
- rtt = ktime_to_us(net_timedelta(last));
-
/* ignore bogus values, this prevents wraparound in alpha math */
if (rtt > RTT_MAX)
rtt = RTT_MAX;
--- a/net/ipv4/tcp_lp.c 2007-07-19 07:08:45.000000000 +0100
+++ b/net/ipv4/tcp_lp.c 2007-07-19 08:20:12.000000000 +0100
@@ -261,13 +261,13 @@ static void tcp_lp_rtt_sample(struct soc
* newReno in increase case.
* We work it out by following the idea from TCP-LP's paper directly
*/
-static void tcp_lp_pkts_acked(struct sock *sk, u32 num_acked, ktime_t last)
+static void tcp_lp_pkts_acked(struct sock *sk, u32 num_acked, s32 rtt_us)
{
struct tcp_sock *tp = tcp_sk(sk);
struct lp *lp = inet_csk_ca(sk);
- if (!ktime_equal(last, net_invalid_timestamp()))
- tcp_lp_rtt_sample(sk, ktime_to_us(net_timedelta(last)));
+ if (rtt_us > 0)
+ tcp_lp_rtt_sample(sk, rtt_us);
/* calc inference */
if (tcp_time_stamp > tp->rx_opt.rcv_tsecr)
--- a/net/ipv4/tcp_vegas.c 2007-07-19 07:08:45.000000000 +0100
+++ b/net/ipv4/tcp_vegas.c 2007-07-19 08:14:49.000000000 +0100
@@ -112,16 +112,16 @@ EXPORT_SYMBOL_GPL(tcp_vegas_init);
* o min-filter RTT samples from a much longer window (forever for now)
* to find the propagation delay (baseRTT)
*/
-void tcp_vegas_pkts_acked(struct sock *sk, u32 cnt, ktime_t last)
+void tcp_vegas_pkts_acked(struct sock *sk, u32 cnt, s32 rtt_us)
{
struct vegas *vegas = inet_csk_ca(sk);
u32 vrtt;
- if (ktime_equal(last, net_invalid_timestamp()))
+ if (rtt_us < 0)
return;
/* Never allow zero rtt or baseRTT */
- vrtt = ktime_to_us(net_timedelta(last)) + 1;
+ vrtt = rtt_us + 1;
/* Filter to find propagation delay: */
if (vrtt < vegas->baseRTT)
--- a/net/ipv4/tcp_vegas.h 2007-07-16 14:25:41.000000000 +0100
+++ b/net/ipv4/tcp_vegas.h 2007-07-19 08:22:33.000000000 +0100
@@ -17,7 +17,7 @@ struct vegas {
extern void tcp_vegas_init(struct sock *sk);
extern void tcp_vegas_state(struct sock *sk, u8 ca_state);
-extern void tcp_vegas_pkts_acked(struct sock *sk, u32 cnt, ktime_t last);
+extern void tcp_vegas_pkts_acked(struct sock *sk, u32 cnt, s32 rtt_us);
extern void tcp_vegas_cwnd_event(struct sock *sk, enum tcp_ca_event event);
extern void tcp_vegas_get_info(struct sock *sk, u32 ext, struct sk_buff *skb);
--- a/net/ipv4/tcp_veno.c 2007-07-19 07:08:45.000000000 +0100
+++ b/net/ipv4/tcp_veno.c 2007-07-19 08:19:37.000000000 +0100
@@ -69,16 +69,16 @@ static void tcp_veno_init(struct sock *s
}
/* Do rtt sampling needed for Veno. */
-static void tcp_veno_pkts_acked(struct sock *sk, u32 cnt, ktime_t last)
+static void tcp_veno_pkts_acked(struct sock *sk, u32 cnt, s32 rtt_us)
{
struct veno *veno = inet_csk_ca(sk);
u32 vrtt;
- if (ktime_equal(last, net_invalid_timestamp()))
+ if (rtt_us < 0)
return;
/* Never allow zero rtt or baseRTT */
- vrtt = ktime_to_us(net_timedelta(last)) + 1;
+ vrtt = rtt_us + 1;
/* Filter to find propagation delay: */
if (vrtt < veno->basertt)
--- a/net/ipv4/tcp_westwood.c 2007-07-18 22:28:38.000000000 +0100
+++ b/net/ipv4/tcp_westwood.c 2007-07-19 08:17:43.000000000 +0100
@@ -100,11 +100,12 @@ static void westwood_filter(struct westw
* Called after processing group of packets.
* but all westwood needs is the last sample of srtt.
*/
-static void tcp_westwood_pkts_acked(struct sock *sk, u32 cnt, ktime_t last)
+static void tcp_westwood_pkts_acked(struct sock *sk, u32 cnt, s32 rtt)
{
struct westwood *w = inet_csk_ca(sk);
- if (cnt > 0)
- w->rtt = tcp_sk(sk)->srtt >> 3;
+
+ if (rtt > 0)
+ w->rtt = usecs_to_jiffies(rtt);
}
/*
--- a/net/ipv4/tcp_yeah.c 2007-07-19 07:08:45.000000000 +0100
+++ b/net/ipv4/tcp_yeah.c 2007-07-19 08:23:08.000000000 +0100
@@ -58,7 +58,7 @@ static void tcp_yeah_init(struct sock *s
}
-static void tcp_yeah_pkts_acked(struct sock *sk, u32 pkts_acked, ktime_t last)
+static void tcp_yeah_pkts_acked(struct sock *sk, u32 pkts_acked, s32 rtt_us)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
struct yeah *yeah = inet_csk_ca(sk);
@@ -66,7 +66,7 @@ static void tcp_yeah_pkts_acked(struct s
if (icsk->icsk_ca_state == TCP_CA_Open)
yeah->pkts_acked = pkts_acked;
- tcp_vegas_pkts_acked(sk, pkts_acked, last);
+ tcp_vegas_pkts_acked(sk, pkts_acked, rtt_us);
}
static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack,
--
next prev parent reply other threads:[~2007-07-19 8:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-19 7:41 [RFC 0/3] TCP congestion control RTT patches Stephen Hemminger
2007-07-19 7:41 ` Stephen Hemminger [this message]
2007-07-19 7:41 ` [RFC 2/3] TCP: cubic - eliminate use of receive time stamp Stephen Hemminger
2007-07-19 10:47 ` Ilpo Järvinen
2007-07-19 7:41 ` [RFC 3/3] TCP: htcp - use measured rtt Stephen Hemminger
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